The invention provides a three-wavelength carrier frequency reuse common-path digital holographic detection device and method. A first color-combining prism is utilized to merge three-wavelength incident laser into one beam, after the one beam sequentially flows through a collimation beam expanding system, a to-be-detected object, a first lens and a non-polarization splitting prism, focusing reference light and object light are formed; the reference light irradiates on a small hole reflector and is reflected; the object light flows through a second color-combining prism and then is divided into three-wavelength object light which respectively irradiates on a triangular reflector and is reflected, the reflected light further flows through the second color-combining prism and is combined into one object light beam; the reflected reference light and the reflected object light are merged through the second color-combining prism into one beam and then flows through a second lens, interference is generated on a light reception surface of an image sensor to form a three carrier frequency reuse hologram, the image sensor is utilized to acquire the hologram which is uploaded to a computer, and a to-be-detected phase is calculated. The method is advantaged in the three light beam common-path structure is employed, the structure is simple, and good stability is realized; only the black white image sensor is needed to record the hologram, and three-wavelength hologram separation is accomplished through the simple algorithm.