The invention relates to a relay second-time close voltage detection device and method based on peak searching algorithm. The device is provided with an ARM processor, a digital-analog converter, a voltage source, a relay coil current signal acquiring circuit, a programmable operational amplifier, a multi-channel analog-digital converter and a touch display, wherein the ARM processor controls theoutput of the digital-analog converter, and controls coil driving voltage with linearly adjustable voltage source output which is linearly increased from low to high; the coil driving voltage is applied to a coil loop formed by a relay coil and a current sampling resistor, and voltage on the current sampling resistor is sent into the multi-channel analog-digital converter for synchronous sampling;the collected signals are subjected to smoothing, two peak positions of the current signals are recognized by utilizing the peak searching algorithm, the coil driving voltages corresponding to the two peak positions are first-time closed voltage and second-time closed voltage; an ARM processor drives the touch display to carry out parameter set, the related curve is drawn, and the first-time andsecond-time close voltages are displayed.