The invention discloses a recyclable drainage device applicable to underground engineering and a construction method thereof. The drainage device is arranged at each of the two ends of a concrete pavement of a foundation pit, and the drainage device and a water retaining device are factory prefabricated parts. The drainage device comprises a plurality sections of sequentially spliced drainage channels prefabricated in a factory, wherein the middle section drainage channel is reverse trapezoidal or U-shaped. According to the recyclable drainage device, a plurality of splicable drainage channels are adopted for replacing traditional drainage ditches, the drainage channels are factory prefabricated parts, the splicing is quick, and after construction, the drainage channels can be repeatedly recycled and utilized, so that the time cost and economic cost of materials are greatly reduced; the adjacent drainage channels are matched at splicing parts through bulges and grooves, so that on one hand, the quick mounting is facilitated, and on the other hand, the sealing performance is improved; the drainage channels are cooperated with a sealant and or rubber waterstops, so that the drainage of water in the underground engineering is effectively guaranteed; and the drainage channels are U-shaped or reverse trapezoidal, so that the manufacturing is facilitated, the drainage amount is large, and the water is quickly drained.