The invention provides an automatic anti-deflection device of a steel sheet back gluer. The automatic anti-deflection device of the steel sheet back gluer comprises a material coil part, a clamping block part, a dust-free cleaning roller and an automatic adjusting mechanism. The automatic anti-deflection device is suitable for the automatic steel sheet back gluer. When the automatic steel sheet back gluer is used, due to the fact that a glue shaft is not stable in the making process, various conditions that adhesive tape is not stable can happen in the uncoiling process, the adhesive tape can easily deflect when attached to a steel sheet during adjustment performed through manual experience, material losses are caused, and a glue roller is contaminated. According to the automatic anti-deflection device, the automatic adjusting mechanism which is monitored in real time is adopted, the position of the adhesive tape can be automatically adjusted in the whole process in real time according to the attaching condition, attaching fluctuation is stabilized within a reasonable error range, and expensive material cost is saved to the maximum extent.