This paper, based on a simplified model, researched the problem of liquid lubricantleakage caused by thermal expansion effects in a self-sealed journal bearing, The analysis indi-cated that mismatch between thermal expansion coefficient of oil-holding-space in bearing, σ_T, andthat of liquid lubricant, α_(oi), is a subtle factor inducing leakage when bearing temperature varies.Measures like properly selecting liquid lubricant and carefully designing bearing structure could betaken to reduce the leakage by matching α_T and α_(oil), Several such ideas concerning bearing mate-rial choosing and structure designing were presented. This paper, based on a simplified model, researched the problem of liquid lubricant leakage caused by thermal expansion effects in a self-sealed journal bearing, The analysis indi-cated that mismatch between thermal expansion coefficient of oil-holding-space in bearing, σ_T, andthat of liquid lubricant, α_ (oi), is a subtle factor inducing leakage when bearing temperature varies.Measures like properly select liquid lubricant and regulated designing bearing structure could betaken to reduce the leakage by matching α_T and α_ oil, Several such ideas concerning bearing mate-rial choosing and structure designing were presented.