A new algorithm evaluation method is presented for coning and large angular rate rotation coexisting environments.Normalized quaternion and its high order items expressed with the rotation vector are used for theoretical error analysis.The performances of two types of different coning algorithms are discussed,one based on conventional frequency-series and the other based on Savages explicit frequency shaping.It is shown that the large angular rotation environment can influence the error characteristics of both algorithms.Generally,the coning algorithm based on Savages explicit frequency shaping is more accurate under coning and large angular rotation coexisting environments.The reason is presented theoretically while the conclusions are verified by numerical simulations.