It is a key to study calibration technique of twin balances used for force-measure-ment test on supporting wingtips in wind tunnel,in which twin balances are used simultaneously to measure aerodynamic loads of the model.Based on measure principle of twin balances,a new complex formula for twin balances is determined,it’s depending on the both calibration formulas for two balances according to spatial force system synthesis principle and interference correction technology among balance components,which is carried out by calibrating the special twin bal-ances separately and synthetically,and is validated with wind tunnel tests.The results show that the calibration technique of twin balances is reasonable and credible,while the maneuverability is well.This technology can serve as the essential theoretical and test basic for the wing-tip support force-measurement test technology wing-tip support.