Thyristor is a main part of fault current limiter（FCL） which will endure bulk current stress during turn-on and conductive process， while existing high power electronics test equipment cannot satisfy the requirement of over-current test. Based on the analysis of thyristor operation condition， equivalent test parameter and method are proposed. According to power electronics equivalent test theory， the losing validity mechanism for thyristor is analyzed. Equivalent test indices are obtained through building over-current test equivalent math model. Referring to the breaker short circuit test method， the stepped test and synthesized test are designed. The stepped test is used to check current steep and current stress with LC oscillation and short-circuit current circuits while synthesized test is used to check current stress of thyristor by turn off and turn on test circuit for breakers. The stepped method is proposed to use through comparing analysis on two methods.