In order to simulate the fault of a single rolling bearing, this paper used the fault diagnosis lab desk to simulate some representative conditions of 30205 type of rolling element bearing, including regular condition, inner ring fault, outer ring fault and rolling body fault. It also adopted fuzzy theory to analyze signals and diagnose faults on the base of the MATLAB software desk. This paper also adopts the amplitude spectrum, the power spectrum, the envelope demodulated spectrum and the delayed correlation-envelop spectrum to diagnosis and analyze simulating signals. Comparatively, the fuzzy diagnosis theory is dependable.