Abstract: As a kind of a mechanical test method,the photoelastic test has been used extensively in the various industrial fields.The petroleum mechanical equipment is consistently thought to be unwieldy because the bad working conditions,on the other hand,the limitations of mechanical calculation which makes the computation be too simple,and sometimes purely the experiential estimation.The attempts of photoelastic tests in the design of 2fz18-14 blowout proventer have obtained the satisfed results.The testing schemes,testing contents,and testing methods introduced in this paper point out a way for the design of complex units.