High voltage, heavy current, miniaturisation and long service life are the current development trend of high voltage switchgear, which would require high heat dissipation performance for the switchgear. In the present paper, based on the finite element method, the heat transfer in the busbar room of KYN28A high voltage switchgear is numerically studied using the electromagnetic-heat-flow coupling model. The heat dissipation performance in the busbar room under natural convection, forced convection, and using a heat pipe are discussed. Firstly, it is found that natural convection alone cannot meet the demand of increasing the current carrying capacity of switchgear. The temperature rise of the contact inside the contact box is higher than 65 ?, which cannot meet the IEEE standard. Secondly, with the forced convection method, the optimal working flow rate of double groups of a fan is 1.5 m/s, and that of a single group of a fan is 2 m/s. With the same inlet air velocity, the heat dissipation performance is better by using double group fans. Finally, it is found that the overheating problem of the contact system can be solved effectively when the fans are combined with heat pipe, and the heat dissipation performance in the busbar room would be good with low inlet air velocity.