Temporary supporting device for municipal engineering pipeline groove and construction method

The invention discloses a temporary supporting device for a municipal engineering pipeline groove. The temporary supporting device comprises four stand columns, two diagonal bridging mechanisms and two transverse baffles. A groove is formed in the middle of one side surface of the upright post in a full-length manner; the four stand columns are divided into two pairs and arranged in the groove in the mode that the connecting lines are in a rectangle shape with the width matched with the width of the groove, and the two pairs of stand columns abut against soil bodies on the two sides of the groove in a one-to-one correspondence mode with the grooves opposite to each other. The two diagonal bridging mechanisms are arranged face to face in the mode of being perpendicular to the length direction of the groove. Each diagonal bridging mechanism comprises two supporting rods and a set of hinging assembly; the two ends of the two supporting rods of each diagonal bridging mechanism are connected with the upper parts a