The invention provides a double passive vision sensing detecting device in GMA material increase manufacturing and a detecting method thereof. The device comprises a working platform, a base plate, a welding gun, a spray nozzle, a width vision sensor, a width composite light filtering system, a height vision sensor and a height composite light filtering system, wherein the width vision sensor is used for monitoring width information of a tail part of an accumulating weld pool; and the height vision sensor is used for monitoring a distance from a spray nozzle to the tail part of the accumulating weld pool. The detecting method comprises a process of processing accumulating dimension images and a process of calibrating the sensing system. According to the double passive vision sensing detecting device in GMA material increase manufacturing and the detecting method thereof disclosed by the invention, accumulating width in GMA material increase manufacturing and feature information of a distance from the spray nozzle to the upper surface of a cladding layer can be monitored simultaneously, so that the real-time detecting problem of cladding width and cladding height in GMA material increase manufacturing is effectively solved; and real-time monitoring and closed-loop control for follow-up accumulating dimension are realized by extracting the feature information of accumulating dimension, so that reliable technical support is provided for real-time control of accumulating quality in GMA material increase manufacturing.