Space gravitational wave detection refers to the method of using satellite formation or constellation to construct a large laser interferometer with interference arms of more than ten kilometers or even millions of kilometers in space to detect gravitational waves. One of the key indicators is that the ranging accuracy of laser interferometry needs to be better than 1~10 pm/Hz^1/2@0.1 mHz~1Hz. In the intersatellite laser interferometer, which was necessary to use the telescope to collimate and expand the laser beam. Due to wavefront distortion of telescope, light field transmitted to spacecraft 2 will deviate from ideal spherical wave during the intersatellite transmission. After coupling pointing jitter of telescope caused by non-conservative forces and other reasons, the phase of light field received by spacecraft 2 will change with the pointing jitter, which will eventually introduce noise in the measurement system. In order to study the error caused by the coupling of wavefront distortion and pointing jitter, the far-field phase distribution with wavefront distortion was obtained by using Kirchhoff scalar diffraction model and Zernike aberration model. After linearization, the phase and displacement noise related to pointing jitter can be obtained. Using this method, the predecessors established the noise generated by the telescope wavefront composed of different order aberrations and wavefront RMS values after far-field transmission, and analyzed the pointing direction of the telescope to reduce the coupling noise and gave how to make the optimal pointing of the telescope close to the intersatellite visual axis to assist pointing. The above research mainly focuses on analyzing the wavefront quality and aberration distribution of the outgoing pupil of the telescope, and the coupling noise can be quickly extracted by linearizing the far-field phase formula. Due to the accuracy loss in the process of linearizing the far-field phase, the numerical simulation is carried out by using the traversal method with higher accuracy and the traditional method. The simulation results show that there is 25%~100% relative error in the coupled noise distribution field in the range of±100 nrad. To solve this problem, this paper uses the differential evolution algorithm to extract the coupling noise, which solves the optimization problem through the process of biological evolution. It can take the jitter range centered on the static pointing of the telescope as search space, randomly select individuals within the jitter range to get the initial displacement, then judge the new individual position by comparing the difference between individuals, finally converge to the extreme value of the function to get the coupling noise. In the same case of wavefront distortion, the relative error between differential evolution method and traversal method is less than 2%. Finally, differential evolution method is used to extract coupling noise and combined with Monte Carlo simulation to give the pointing jitter index of the telescope transmitter required to achieve the gravitational wave measurement accuracy when different wavefront quality RMS values are given. The simulation results show that if the RMS value of the telescope wavefront quality is λ/60~λ/20, for the couple noise of 10 pm/Hz^1/2@0.1 mHz~1 Hz, the pointing jitter of the transmitting telescope should be about 19~34 nrad/Hz^1/2@0.1 mHz~1 Hz, and the pointing jitter corresponding to the noise index of 1 pm/Hz^1/2@0.1 mHz~1 Hz should be better than 2.1~7.0 nrad/Hz^1/2@0.1 mHz~1 Hz. According to the existing design parameters of the outgoing pupil wavefront RMS value of λ/30 in LISA, Taiji and Tianqin, the pointing jitter needs to be better than 21 nrad/Hz^1/2 @0.1m Hz~1 Hz and 2.2 nrad/Hz^1/2 @0.1 mHz~1 Hz respectively in the measurement frequency band. This result provides a target and reference for the manufacturing and pointing control system of the telescope in the later stage.