The invention discloses a green sand water content measuring device and a water content measuring method based on the same, and relates to the field of casting detection. The problems that when the water content is calculated by measuring a green sand capacitance by means of an existing capacitance method, the measuring precision is not high due to the influence of the electrified resistance are solved. The measuring device is composed of a green sand water content signal pickup module, a signal cycle measuring module, a gate, a square operation module, a reference voltage module, a zero setting module, a differential motion amplification module, a calibration module, an A/D conversion module, an ARM measurement and control system and a water content display module. The measuring method comprises the following steps that 1, green sand is added; 2, the green sand water content signal pickup module obtains electric signals u(t); 3, the signal cycle measuring module measures the cycle Tx of u(t); 4, the zero setting module outputs a zero setting signal T0; 5, a differential signal is obtained through calculation of the calibration module; 6, the ARM measurement and control system calculates the volume water content. The green sand water content measuring device and method are applicable to measurement of the green sand water content.