The latest edition of ’Technical code for building slope engineering（GB 50330-2013）’ employs a novel seismic active earth pressure formula of retaining wall.However

there exists a certain degree of deviation when seismic earth pressure is calculated by using the formula in the code

and the height of action point of seismic earth pressure has not been given.Based on research results in the literature

we develop a complete derivation of the formula and the action point height of seismic earth pressure

and point out the mistake existed in the code（GB 50330-2013）.The transformation method with a rotating computational model of retaining wall is adopted in the formula derivation

in which the seismic active earth pressure computing problem is converted into non-seismic active one.Therefore

the active earth pressure formula for non-seismic condition is developed by applying mechanically derivation process of the active earth pressure.The earth pressure calculating parameters are utilized by rotating earthquake angle.This achievement simplifies the complex solution procedure for the active earth pressure.