To address the problem that non-vertical installation of suction pile can easily lead to shallow soil instability and wellhead overturning, a study on verticality control of suction piles with different diameters and installation depths was conducted through a combination of theoretical analysis and simulation tests. A calculation method for verticality control of suction piles in deepwater oil and gas well construction was proposed based on the structural dimensions of the suction pile and the properties of the formation soil and was validated through simulation tests. The results show that the diameter of the suction pile, the penetration depth of the suction pile, and the properties of the seabed soil are the main factors affecting the verticality control of the suction pile. Under the same other conditions, a smaller diameter of the suction pile and a shallower penetration depth pose higher verticality control requirements on the wellhead. To ensure the stability of the deepwater seabed wellhead, the inclination angle of the suction pile wellhead shall not exceed 6°.