Abstract: The phase difference (i.e., time difference) and amplitude difference between the geomagnetic data of the offshore work area and the geomagnetic diurnal variation data of the remote stations are still challenges to the precision of the marine magnetic survey network. Based on the stations on both sides of the East China Sea and three stations in Europe at higher latitudes, this study analyzed and made statistics on the numerical differences in morphological characteristics, phase differences, and amplitude differences of the diurnal variation curves during the daytime, nighttime, and the periods of intense magnetic disturbance. The results are as follows. During the daytime, the phase difference between the stations is constantly changing, resulting in a large amplitude difference around noon. During the nighttime, the data of the stations have consistent phases, and the amplitude difference is mostly less than 4 nT. During strong magnetic disturbance activities such as magnetic storms, the phases of the stations are consistent, and the amplitude difference is even smaller than that during quiet days. According to the survey data of the ocean, the absolute value of the difference at intersections between the survey lines during magnetic storms and quiet days is less than 3.2 nT. The variation characteristics of the phase difference and amplitude difference of the geomagnetic diurnal data between stations facilitate the diurnal variation correction of the marine geomagnetic data.