The utility model discloses an excavation construction auxiliary device, include main part, reflection member, drum, the 2nd beam emitters who is used for showing excavation depth's a beam emitters and is used for showing the plane elevation, reflection member, drum, a beam emitters and the 2nd beam emitters all fix in the main part, a beam emitters's ray direction is perpendicular with the 2nd beam emitters's ray direction. Erect the reflection member on the main part is measured to the total powerstation of excavation construction site or half station appearance to the accuracy of calibration excavation construction auxiliary device mounted position. The level of acting as go -between of drum was pulled out to the during operation daytime, can show the plane elevation. With acting as go -between to measurement department of drum, can learn excavation depth through the mode of measuring. When working at night, with the vertical setting of a beam emitters and open and shine in mark department, can reflect directly perceivedly whether excavation depth meets the demands. With the 2nd beam emitters level setting and open, can show the plane elevation.