The invention provides an improved determinator for measuring static lateral pressure coefficient of soil. Four pressure sensors, a weighing conjunction box and a weighing display controller are added to an present determinator; the four pressure sensors are placed on the upper part of a base and the bottom of a sample tube of the determinator for measuring static lateral pressure coefficient of soil, in order to replace the support pads for support the sample tube, and to measure the friction force between the sample and the sample tube side wall; the pressure sensors are respectively connected with the weighing conjunction box; the weighing junction box is connected with the weighing display controller; the weighing junction box summarizes the stress signals of the four weighing sensors, adjusts the angle difference, and finally transfers the summarized the stress signals to the weighing display controller; the weighing display controller receives the summarized the stress signals input by the weighing conjunction box, and displays the total sum of the pressure on the four pressure sensors, wherein the displayed total sum is the side wall friction force. The invention has the advantages of usage convenience, and accurate determined result.