Considering the influence of sealing medium pressure,gasket size effect and preload,the leakage tests of nonasbestos rubber gaskets under different working conditions were conducted.The relationships between leakage rate and medium pressure and pretightening stress of the gaskets with different sizes were obtained.The results show that the leakage rate is decreased with the increase of gasket size and pretightening stress,and it is decreased with the increase of medium pressure.Due of the low fitting accuracy of the porous leakage model to the test data under the influence of multifactor conditions,the porous leakage model was modified.Compared to previous model,the prediction results of the improved leakage model are closer to the experimental values,which indicates that the improved porous leakage model can effectively predict the leakage rate of non asbestos rubber gasket.