The invention discloses a method for monitoring the longitudinal force of a seamless rail symmetrically and precisely based on the bidirectional strain method. The method for monitoring the longitudinal force of the seamless rail symmetrically and precisely based on the bidirectional strain method comprises the steps that (1) a basic testing bridge circuit is used for testing the strain, and four strain gauges are attached to the detected rail, wherein the strain gauge R1 and the strain gauge R2 are symmetrically arranged on the two sides of the rail web of the detected rail, the strain gauge R3 and the strain gauge R4 are symmetrically arranged on the upper surfaces of the two sides of the bottom of the detected rail, the Wheatstone full-bridge testing bridge circuit is adopted, the strain gauge R1 and the strain gauge R2 are symmetrically arranged, and strain gauge R3 and the strain gauge R4 are symmetrically arranged; (2) the longitudinal force of the target rail is obtained through calculation according to the strain epsilon obtained in the step (1). According to the method for monitoring the longitudinal force of the seamless rail symmetrically and precisely based on the bidirectional strain method, with the rail bidirectional strain method as the standard, the site factors such as the heat output difference of the strain gauges, the temperature differences between different positions on the same rail section and the temperature difference between a compensation rail and the detected rail under different constraint conditions are considered, the influences of various kinds of buckling strain are balanced, and the testing precision of the longitudinal force of the seamless rail is improved.