The five common methods used residual strength assessment for oil and gas pipeline were studied.By comparing the results calculated by strength assessment equations and measured by blasting experiments, the calculation error of these equations were obtained.Then the error distribution interval was analyzed.The results showed that the equation of Modified B31G was less conservative than Origin B31G.Allowable stress method and PCORRC equation had the better evaluation results.The evaluation equation given by API 579-1 standard also had the problem of too-conservative evaluation results.For the different grade pipeline steels, the evaluation effects of the same evaluation equation were different.