The utility model provides a manual breaking shear for a heat insulation layer, and belongs to the technical field of oil equipment inspection tools. The technical scheme is as follows: the manual breaking shear mainly comprises a first knife handle, a first knife bit located at the front end of the first knife handle, a second knife handle hinged with the first knife handle by a hinge shaft, and a second knife bit located at the front end of the second knife handle. The manual breaking shear is characterized in that the cutting edge of the first knife bit is intersected with that of the second knife bit to form a cutting surface; a bending deflected to one side of the hinge shaft is arranged at the junction of the first knife bit and the first knife handle, and a U-shaped bending bent towards the outer side of the second knife bit is arranged close to the bending of the hinge shaft. The manual breaking shear provided by the utility model has the beneficial effects of being easy to insert, shear, propel and exert a force; a shearing opening is regular in structure and easy to repair; the manual breaking shear is simple in structure, labour-saving, and capable of saving shearing time.