The invention discloses a method for improving the sewage treatment speed in a low temperature environment, which is characterized in that a biological reaction tank is arranged in a greenhouse which comprises a support frame, a transparent material layer and a heat insulating material layer, wherein the transparent material layer is covered on the support frame, and the heat insulating material layer is covered on the transparent material layer. The invention has the advantages that: 1, the cost is low and the investment is less, and the adopted materials has low price, are easily purchased from northern area, and one-time investment is less; 2, the maintenance cost is low, and after the frame of the greenhouse is constructed, plastic and mats are replaced for one time within 2 to 3 years according to service conditions; 3, the operation is simple and easy, and the indoor temperature can be timely adjusted according to an indoor thermometer and weather situation; and 4, the energy-saving effect is obvious, and main source of temperature rise comprises solar energy and heat energy generated by a blower of the biological reaction tank during the aeration.