Gravity data are indispensable in determining the source rupture model and obtaining preliminary earthquake information. To analyze the gravity variation caused by a dislocation on the earth's surface due to an earthquake, we calculate the gravity variation characteristics of a typical fault slip (strike- and dip-slip). Based on the results obtained using the Okubo dislocation theory formula, we observe the following: (1) the total gravity variation caused by vertical strike-slip faults exhibits a four-quadrant symmetrical distribution. The magnitude of the gravity variation at locations with the same azimuth near the epicenter gradually decreases with the distance from the fault; for the same rupture geometry and slip, the magnitude of the gravity variation near the epicenter decreases as the depth of the rupture center increases, while the magnitude of the gravity variation away from the epicenter exhibits a slower decrease. (2) The gravity variation at the hanging walls of the dip-slip fault is generally smaller than that at the footwall; for dip-slip faults with the same rupture geometry and slip, the maximum value of the gravity variation decreases with the distance as the depth of the rupture center increases. To analyze the gravity variation caused by the Menyuan earthquake in 2022, the coseismic rupture model of the earthquake is selected, and the total gravity variation around the epicenter is calculated by superimposing the gravity variations caused by subruptures. The results show that the gravity decreases in the northeast and southwest directions away from the epicenter; its minimum value is -8.82 μgal. Additionally, it increases in the northwest and southeast directions away from the epicenter; its maximum value is 28.28 μgal. The area where the gravity increases is smaller than the area where the gravity decreases.The gravity in the Menyuan station near the epicenter increases by 3.40 μgal, which can be monitored using gravity measurement instruments. The gravity variation measured by other stations located around the epicenter is less than 1 μgal. When monitoring and analyzing the long-term gravity variation in this region to reveal its tectonic activity, the gravity variation caused by the Menyuan earthquake should be deducted.