The invention relates to the technical field of flight load measurement, and provides a flight load measuring method of a rocket chamber section with a rod structure. The method comprises the following steps: S1, acquiring bending strain data and axial strain data of a target rocket in a flight process by a measurement bridge circuit formed by strain sheets distributed on inclined rods of the target rocket; S2, measuring a constitutive model by the rocket structure load based on the bending strain data and the axial strain data to acquire bending load and axial load of the target rocket in the flight process. According to the flight load measuring method of the rocket chamber section with the rod structure disclosed by the invention, by building a group bridge circuit which is decoupled respectively by axial force, bending moment and shear load of the rod structure of the rocket, strain data of the rocket in the flight process are acquired; by combination with a ground calibration test, the relation between the strain and the load of the target rocket is acquired, the load measurement of the rocket in a practical flight process is realized, the measurement deviation can be effectively eliminated or reduced, and the accuracy of the flight load measurement of the rocket is improved.