To study the working behavior of a rigid pile composite foundation of high-rise buildings, an in-situ loading test and stress test on piles and soil were carried out. According to the test results, the stress distributions and variations, load transferring characteristics, and stress distributions of piles were analyzed. The results showed that the piles with the formation of non-soil compaction technology can consolidate soil among piles. When the load level was greater than 240 kPa, a better consolidation effect can be obtained. The development negative friction at the top of piles was relevant to the load level. The adjustment effect of cushion on the composite foundation was mainly embodied before the load level reached the characteristic bearing capacity of the composite foundation. Under vertical load, the stress distributions along the internal and external sides of pile shaft were different and the loading plate would bring influence to stress distributions of the pile shaft. The influence range was from the middle to the top of the pile. Based on the test results, it is recommended to reduce the evaluation standard of the bearing capacity determined in the pressing plate test. The results can provide a reference for similar engineering.