Rail track geometric parameters, such as gage, level, twist, longitudinal irregularity, alignment irregularity, etc., have much influence on the operation safety of train vehicles. With the development of railway, the demand for measuring track geometric parameters precisely and efficiently has become a common concern, and to date this problem has not been properly solved. In this work, a new measurement method and a system for track geometric parameters are presented. Through analyzing advantages and disadvantages of existing measurement methods of track geometric parameters, a fiber-optic gyro is adopted for the straightness measurement. It greatly eliminates the measurement errors caused by existing methods. The feasibility of this track parameter measurement trolley is proven by practical experiments.