In-situ loading tests are usually used to test the performance of doubtful building component structures. Different codes have different load requirements for in-situ loading tests. In order to understand the selection of test loads under different conditions, the loading schemes, basic process and test analysis results of in-situ loading test of reinforced concrete floor slab are first introduced, and then the value and calculation of test loads under different specifications with engineering examples as the background are further discussed, finally, the application of test loads for component suitability test, component bearing capacity test and component bearing capacity test under normal use are analyzed. The results show that the calculation method of Technical standard for inspection of building structure should be used for the test of component suitability, the test method of GB/T 50784—2013 should be used for the test of component bearing capacity under normal use, and the test method of Technical standard for inspection of concrete structure should be used for the test of component bearing capacity. The results can provide some references for the load value of in-situ load test to component bearing capacity. The results can provide some references for the load value of in-situ load test.