The invention discloses a measuring and calculating method of axial stress of concrete support. The method specifically comprises the steps of firstly setting five monitoring points from one end of a center shaft of the concrete support to the other end equidistantly in sequence, and installing one concrete strain force meter at each monitoring point in the axis direction; secondly recording frequency initial values, minimum reading values of dependent variables and real-time measured frequency values of the concrete strain force meters of the five monitoring points respectively, and calculating the dependent variables of the concrete strain force meters corresponding to the five monitoring points respectively; thirdly calculating axial stress exerted on the cross section of the concrete support at each monitoring point on the concrete support; finally conducting weighted average summation and calculating the axial stress practically exerted on the concrete support according to the axial stress at each monitoring point. According to the measuring and calculating method of the axial stress of the concrete support, the problems that an existing technology measuring value is far bigger than a design value, accordingly on the condition that the concrete support is not damaged practically, foundation pit engineering construction is shut down, support structures are added additionally, the cost is increased, and the construction period is delayed are solved.