At present, there are many studies on the small-angle oblique underpass in shield tunneling projects. To better control the associated deformations, relevant control measures were studied. Taking the underpass project of the tunnel section from Xiyuzhuang Station to West Station of the northern section of Tianjin Metro Line 4 as the research object, the process of small-angle oblique underpass by the shield machine was simulated using finite element software. The effects of secondary grouting and annular gap filling of the shield shell were studied, and the differences in deformation and stress of existing tunnels at different sections were analyzed. The results show that the efficiency of secondary grouting is about 38% during the underpass of the first line and about 6% during the underpass of the second line. The disturbance degrees at different points of the same section are different, resulting in significant spatial effects of deformation. The maximum settlement positions of the left line left track and the right line right track have a distance difference of 10 ~ 13 meters, and the maximum horizontal deformation positions have a distance difference of 2 ~ 4 meters. After the twin lines pass, the annular gap filling of the shield shell significantly reduces the deformation range and maximum deformation value of the existing tunnels, with the maximum settlement value of the tunnel decreasing by 30.3% and the maximum horizontal displacement decreasing by 36.4%. After annular gap filling of the shield shell, the overall settlement control efficiency of the twin lines during the underpass process is roughly stable at 30% ~ 35%, and the control efficiency during the underpass period is good. The horizontal deformation control efficiency is generally below 30%, and the control efficiency before the underpass is good. Under different cross-section conditions, the existing tunnels with greater flexural rigidity experience less deformation. The box-shaped cross-section has a slight diffusion effect on soil settlement, while the circular cross-section existing tunnel hinders the development of soil settlement, reducing surface settlement.