The survey line layout is the primary content of the technique design in marine gravity survey, which has decisive effect on assurance of the survey precision and efficiency. Survey line layout involves two aspects:One is the choice of line direction; the other is the determination of line spacing. The line direction should be as perpendicular as possible to the direction of the gravity anomaly contour; the line spacing should be widened as much as possible to meet the requirements of the accuracy of the results, in order to reduce the workload and improve the measurement efficiency. Given no sufficient consideration to the characteristics of the gravity anomaly, the line spacing is decided by survey assignment at present. The precision of EGM2008 model gravity anomaly is high in marine area; it can be used as priori information for the layout of marine gravity measurement lines. Based on the characteristics of marine gravity measurement, the EGM2008 model is used to estimate the spacing of marine gravimetric survey lines under the premise of meeting the accuracy requirements. The measured data is further used to verify the reasonableness of the survey line spacing layout. The results show that applying EGM2008 model to estimating the line layout spacing can meet accuracy requirements in marine gravity survey, which can provide the quantitative index for the optimizing of the survey line layout.