AbstractAirborne gravimetry is a new technique for determination of earth gravity, in which gravimeter, GPS and other sensors are used. Its basic theory is that gravimeter senses the total accelerations including gravity acceleration, inertial acceleration and some other accelerations; and GPS determines inertial acceleration of moving‐base; then gravity will be yielded if inertial acceleration can be subtracted from total accelerations with some corrections. Therefore, determination of inertial acceleration by using GPS is one of the key problems to airborne gravimetry. Firstly, the mathematic model of direct calculation method is deduced in this paper. Then, data from an airborne gravimetry test are processed. Finally, the acceleration precision is evaluated in static and kinematic condition respectively. The results indicate that the acceleration accuracy of 0.4~0.9 mGal level can be achieved at 60 s interval in static condition and 1~3 mGal level can be achieved at 90 s interval in kinematic condition.