The paper points out, before Tangshan earthquake and during its active period in 1976, a clear change of gravity field oecured in the east part of Beijing network. The ehange has a reverse mark to the gravity anomaly in earthquake foci area.

• 本文指出,在1976年唐山地震前以及其活动期间,北京测网东部的重力场发生明显的变化,且呈现与震源区重力异常符号相反的变化特征。