The invention discloses a measuring method of tensile force of a bridge pull rod and a device thereof. In the method, a group of pressure parts and a group of non-pressure parts are respectively arranged between the pull rod anchor head pressure end surface and the bridge pressure end surface, so as to lead the supporting force of the bridge pressure end surface to be applied on the pressure end surface of the pull rod anchor head through the pressure parts, and lead the non-pressure parts to be applied with no force; capacitors with identical specification are arranged in each pressure part and non-pressure part; the directions of the battery lead plates of the capacitors are identical with the directions of the pressure surfaces of the pressure parts; the capacitors in all the pressure parts are arranged in parallel; the capacitors in all the non-pressure parts are arranged in parallel; the two groups of capacitors are connected into a signal processing circuit and are operated therein, so as to measure the size of the capacitance of the capacitors in the pressure parts and the size of the capacitance of the capacitors in the non-pressure parts; the size of pressure of the pressure parts can be converted according to the difference of the two measuring values, and the pressure is equal to the tensile force applied to the pull rod. The invention is characterized by precise measurement, wide measuring range, insusceptibility to environment interference, realization of online monitoring and the like.