The geometric model of inverted threelobe pressure dam bearing was built,and the distribution of oil film thickness was analyzed.The theory model of sliding bearing was established based on Reynolds equation.The carrying capacity of the sliding bearing was obtained by using unit flow balance method to discretize the Reynolds equation of complex structure lobe and using MatLab to solve difference equation.Combining the load conditions with pattern search,the static characteristic of bearing was got with fixed load orientation,and the oil film thickness distribution as well as the pressure profile was also got.By changing different structural parameters of bearing in proportion,respectively,the effects on load capacity by each parameters of the bearing were analyzed.The results show that the effects of ellipticity and lengthtodiameter ratio of bearing on the load capacity are larger,while the effects of other parameters are smaller.With the increasing of ellipticity and lengthtodiameter ratio,the load capacity of the sliding bearing is increased.