The invention relates to an earth excavation device applied to a pipe roofing method and an excavation method thereof. A pipe roof is arranged inside the soil body. The earth excavation device comprises a walking mechanism capable of walking in the pipe roof and a cutting mechanism which is arranged on the front side of the walking mechanism and used for cutting the soil body. According to the earth excavation device applied to the pipe roofing method, the earth excavation device keeps going forward, and meanwhile, the soil body is cut; cooperation between all components of the device is comparatively good; and thus construction efficiency is improved.