Abstract: Through practice, it is proved that the bored reinforced concrete cast-in-situ pile （cast-in-situ pile） foundation is one of the very ideal form of sluice foundation. The construction of the pile and the calculation method used for the cast-in-situ are still not perfect, because for a short time the cast-in-situ pile is used. So we have to do some necessary pile foundation tests when we are making some important projects. It is only through such tests that we can determine the bearing capacity of the cast-in-situ pile foundation more reasonable and more reliable. But it is very difficult to do such tests, because sluice foundation has a large number of piles, a big body of pile group and a large bearing capacity. It is generally to do a single pile test and then use the data obtained from this test to determine the bearing capacity of pile group. It is well known that the construction and the mechanism are quite different between single pile and pile group. They can't be compared. So the data obtained from the single pile tests are not the reflection of that from pile group, especially when the pile spacing is varied. In order to overcome the difficulty of pile group tests,we carried out the small bored cast-in-situ pile tests, and studied the characters of single pile, two-pile and pile group. The relationship between two-pile and pile group to take the place of the relationship between single pile and pile group is recommended.