Early warning circuit for roof to be collapsed due to accumulated snow

The utility model provides an early warning circuit for a roof to be collapsed due to accumulated snow. The early warning circuit comprises a power supply, a deformation sensor, and an alarm circuit, wherein the deformation sensor is connected between the power supply and the alarm circuit. The deformation sensor comprises a fixed plate, a mercury switch fixed on the fixed plate, a stay rope with one end fixed on the fixed plate, a spring with one end fixed on the fixed plate, the fixed plate of the deformation sensor is fixed at a first end of a second purlin of an indoor ridge, the second purlin bears pressure of the roof and is the easiest to be stressed and deform, the other end of the spring is fixed at the innermost end of the first end of the second purlin of the ridge, the other end of the stay rope extends along the second purlin of the ridge to be fixed at a second end of the second purlin of the ridge, and the mercury switch is connected between the power supply and the alarm circuit. The early war