In the artificial fitting of spatially correlated multi-point ground motion，the response spectrum and peak value of acceleration at different supporting points of long-span structures are generally the same，while the peak values of corresponding displacement time history at different input points are different. In order to study the effects of ground motion characteristics and different displacement control conditions on structural response，two different envelope functions are introduced to simulate the intensity and frequency nonstationary characteristics of ground motion in this paper，and six groups of spatially correlated multi-point ground motions are fitted by controlling the same peak value of acceleration or displacement in the earthquake time history of different support points. Then，the nonlinear response analysis of three span continuous beam bridge is carried out by using the multi-point acceleration/displacement input mode. The results show that：the peak value of the displacement time history has a great influence on the internal force and displacement response of the structure，the larger the displacement peak value is，the larger the structure response is，the stronger the degree of nonlinearity is，and there is no obvious correlation with the shape of the displacement time history；in the simulation of ground motion with acceleration response spectrum and acceleration peak，the discreteness of the corresponding displacement peak at each support point is relatively large，in order to ensure the safety of the structure，the minimum value of the displacement peak should be controlled in the spatially correlated multi-point ground motion fitting；the frequency non-stationary characteristic of the acceleration time history has obvious influence on the displacement of the bridge and the torque of the piers，if only considering the non-stationary characteristic of the seismic intensity，there is a risk of underestimating the structural response. Therefore，in the seismic analysis of long-span structures，the time-space coupling characteristics，non-stationary characteristics and the minimum peak value of displacement input should be reasonably described，and the nonlinear response of the structure should be fully estimated to ensure the safety of the seismic design of the structure.