High quality ion beams are required by IMP cyclotron and atomic physics research, so it is important to research and measure beam emittance of ECR ion source. Intense beams extracted from ECR ion source usually have low energy, so it is suitable to use Electric-Sweep Scanner to measure the emittance. This kind of measurement is popularly used at ECR ion source, and it has some prominent merits such as high accuracy, very short time of data processing and easy expressing of the emittance pattern. So we designed and built this emittance scanner to measure emittance of the ion beams produced by LECR3 ion source. The structure of the ESS is shown in Fig.1, and the photo of the ESS is shown in Fig.2. High quality ion beams are required by IMP cyclotron and atomic physics research, so it is important to research and measure beam emittance of ECR ​​ion source. Intense beams extracted from ECR ion source usually have low energy, so it is suitable to use Electric-Sweep This kind of measurement is popularly used in ECR ion source, and it has some prominent merits such as high accuracy, very short time of data processing and easy expressing of the emittance pattern. So we designed and built this emittancetance The structure of the ESS is shown in Fig. 1, and the photo of the ESS is shown in Fig. 2.