Silicone rubber adhesive has good low temperature resistance, so it is often used in the bonding process of composite substrate of cooled infrared detector. The effect of the primer on the bonding strength of silicone rubber was studied. The tensile results show that the average bonding strength of the sample directly bonded was 4.07 MPa at liquid-nitrogen temperature, while the average bonding strength of the sample pretreated with the primer reached 6.34 MPa. In addition, by observing the fracture surface of tensile sample, it is found that more silicon rubber remained on the fracture surface of the sample pretreated with the primer. Therefore, pretreatment with the primer can effectively improve the bonding strength of silicone rubber, which is helpful to improve the reliability of infrared detectors.