Building engineering cost teaching demonstration device

The utility model discloses a constructional engineering cost teaching demonstration device which comprises a base, a supporting rod, a fixing column and a collecting box are arranged above the base, the fixing column is located between the supporting rod and the collecting box, a blackboard is arranged above the fixing column, a collecting box and a first magnetic block are arranged on the front surface wall of the blackboard, and the collecting box is connected with the first magnetic block. The first magnetic block is located above the collecting box, a collecting groove is formed in the top end of the collecting box, drainage holes are formed in the inner surface wall of the collecting groove, a second magnetic block is attracted to the front surface wall of the first magnetic block, a plastic cover is fixed to the front surface wall of the second magnetic block through glue, and a supporting plate is installed above the supporting rod. Some water can be stored in advance through the water storage tank, t