The invention discloses a system for increasing the power density of a machine room. The system comprises at least one server machine cabinet with a cabinet door, and an air conditioner, wherein the cabinet door is arched to the left side so as to form an air supply channel which is used for receiving cold air supplied by the air conditioner and leading to the rear end of the server machine cabinet; an air inlet is formed at one end of the cabinet door and a closed baffle plate is arranged at the other end of the cabinet door; the air conditioner supplies the cold air to each server machine cabinet through an air supply main pipe; one end of the air supply main pipe is connected with the air outlet of the air conditioner and the other end of the air supply main pipe is connected with the air inlet of the corresponding cabinet door through each air supply branch pipe; and a fan is arranged in each air supply branch pipe. The system is low in energy consumption, simple in structure and low in cost; the cabinet door is outwards arched to form the air supply channel so as to cool the server machine cabinet one to one; therefore, energy consumption caused by mixing of the cold air and hot air can be avoided and energy consumption of a data center can be reduced effectively; and under the same refrigeration power, the installation density of a server can be increased effectively.