An inner slide rail mounting structure for a two-stage server slide rail includes an outer rail, a front bracket, a rear bracket, an outer rail reinforcement bar and an inner rail. The front bracket is affixed to a front end of a front bracket supplementary rail that is slidably inserted into the outer rail reinforcement bar. The rear end of the front bracket supplementary rail is connected with a spring plate that has one end thereof connected to the outer rail reinforcement bar through a tension spring and an opposite end thereof fixedly connected with an outer rail ejection control plate that has an abutment portion abutted against the outer rail reinforcement bar and a press portion extended from the abutment portion for pressing by the user to release the abutment portion from the outer rail reinforcement bar.