The invention discloses a computer case which can efficiently dissipate heat and is excellent in protection performance. First openings are formed in the two sides of the machine box, a second openingis formed in the other side of the machine box, a power mechanism is arranged on one side of the top in the machine box, a first synchronous belt is arranged on the power mechanism, a reciprocating transmission mechanism is arranged on the first synchronous belt, and a vertical plate is arranged on the reciprocating transmission mechanism. According to the invention, the fan blades can do reciprocating motion during rotation; efficient flow of air is facilitated, the quality of air entering the case can be ensured; therefore, efficient and high-quality heat dissipation can be carried out in the case; and the rotating speed of the fan blades can be automatically controlled, adjustment can be conveniently conducted according to the use condition of equipment, the heat dissipation quality isbetter guaranteed, the temperature in the case is effectively reduced, protection can be effectively conducted, external collision can be effectively resisted, the stability of the case is guaranteed, and the service life of internal parts of the case can be prolonged.