Abstract: The formula of acting force on pile top of foundation with asymmetric piles was deduced． Analysis showed that the formula of Technical Code for Building Pile Foundations ( JGJ 942008) was a special case，which was only applicative with the situation of symmetric arrangeing piles and selecting the origin of coordinates should be careful when the formula was used，centroid of pile group instead of centroid of cushion cap should be selected as the origin of coordinates． Meanwhile，through analysis results of the formula， larger calculation error appeared on the asymmetric piles using the formula of JGJ 942008． When calculating acting force on pile top，designer should choose the reasonable formula according to real situation．