Formwork positioning device and ditch construction method

The invention discloses a formwork positioning device and a ditch construction method.The formwork positioning device comprises a fixing plate, a height adjusting assembly, a horizontal adjusting assembly and a positioning piece, and the fixing plate is used for being installed at the bottom of a ditch; the height adjusting assembly comprises a vertical adjusting rod and a first mounting seat, the vertical adjusting rod is mounted on the fixing plate, and the first mounting seat is configured to be capable of adjusting the height of the first mounting seat on the vertical adjusting rod; the horizontal adjusting assembly comprises a horizontal adjusting rod and at least two second mounting seats, and the second mounting seats are configured to be capable of adjusting the positions of the second mounting seats on the horizontal adjusting rod; and the positioning piece is mounted on the second mounting seat, and is clamped and matched with the top of the template. The height of the positioning piece is adjusted