In order to improve the accuracy of detecting the compressive strength of thin-walled precast concrete components in agricultural water conservancy projects using small-diameter core samples, this article collects and organizes relevant drilling core method test data in China, analyzes the influence of coarse aggregate types in concrete on the compressive strength of different diameter core samples and their fitting lines with the compressive strength of standard size cubic specimens, and uses the least squares method to regress the strength measurement formula of small-diameter core samples. The results showed that the type of aggregate had little effect on the compressive strength and its correlation curve of the 40 mm diameter core sample, but had a significant impact on the compressive strength and its correlation curve of the 60mm diameter core sample; Based on literature experimental data, the fitted small diameter core sample method strength measurement formula has high detection accuracy and can be selected for application according to specific detection conditions. The research results can provide reference for the quality control of concrete strength in water conservancy and civil engineering structures.