The present article deals with the Chinese invention of time-keeping apparatus. Mention is made of the sundial and the clepsydra invented about 3000 years ago, but the emphasis is laid on the invention and development of mechanical clockworks. first of all, three reasons are given to prove that the Chinese water-powered astronomical apparatus equipped with mechanical clockworks was first invented by Chang Heng, that is about 130 A.D. Then the article points out that during the period of about 600 years from the time of Chang Heng to the beginning of the T’ang Dynasty the invention and application of the odometer exercised a considerable influence on the development of clockworks in and after the T’ang Dynasty, for both the odometer and the clockwork represent the application of gear trains which reduce the speed gradually. Then a detailed analysis is given of the water-powered astronomical apparatus and the time-keeping mechanisms devised in the T’ang Dynasty by I-Hsing and Liang Ling-tsan during the years of the reign title K’ai Yuan (about 725 A.D.), and in the Sung Dynasty by Chang Sze-hsun during the years of the reign title Tat-Ping-Hsing-Kuo (about 980 A.D.), by Su Sung and Han Kung-lien during the years of the reign title Yuan Yu (about i086-1089 A.D.) and by Wang Fu in the 6th year of the reign title Hsuan Ho (1124 A.D.). The final stage of development was reached with the independent mechanical clockwork of Kuo Shouching made in the 13th year of the reign title Chih Yuan (1276 A.D.) of the Yuan Dynasty and that of Chan Hsi-yuan made in the first years of the Ming Dynasty (about 1360 A.D.). If we count from the time of Chang Heng, the Chinese invention of clockworks has a priorty of twelve hundred years over that of the west. Even if we count from the time of the reign title K’ai Yuan of the T’ang Dynasty, the Chinese invention is still earlier by six hundred years. The present article deals with the Chinese invention of time-keeping apparatus. Mention is made of the sundial and the clepsydra invented about 3000 years ago, but the emphasis is laid on the invention and development of mechanical clockworks. First of all, three reasons are given to prove that the Chinese water-powered astronomical apparatus equipped with mechanical clockworks was first invented by Chang Heng, that is about 130 AD Then the article points out that during the period of about 600 years from the time of Chang Heng to the beginning of the T’ang Dynasty the invention and application of the odometer exercised a considerable influence on the development of clockworks in and after the T’ang Dynasty, for both the odometer and the clockwork represent the application of gear trains which reduce the speed gradually. Then a detailed analysis is given of the water-powered astronomical apparatus and the time-keeping mechanisms devised in the T’ang Dynasty by I-Hsing and Liang Ling -tsan during the years of the reign title K’ai Yuan (about 725 AD), and in the Sung Dynasty by Chang Sze-hsun during the years of the reign title Tat-Ping-Hsing-Kuo (about 980 AD), by Su Sung and Han Kung-lien during the years of the reign title Yuan Yu (about i086-1089 AD) and by Wang Fu in the 6th year of the reign title Hsuan Ho (1124 AD). The final stage of development was reached with the independent mechanical clockwork of Kuo Shouching made in the 13th year of the reign title Chih Yuan (1276 AD) of the Yuan Dynasty and that of Chan Hsi-yuan made in the first years of the Ming Dynasty (about 1360 AD). If we count from the time of Chang Heng, the Chinese invention of clockworks has a priorty of twelve hundred years over that of the west. Even if we count from the time of the reign title K’ai Yuan of the T’ang Dynasty, the Chinese invention is still earlier by six hundred years