This invention relates to a sealing structure of a turbine booster characterizing in the sealing of a compressor: a V-type seal loop is enclosed on the outer jacket of an inner rotor shaft of a cover base, the end surface of a graphite seal loop is adhered with the supporting end surface of the rotor shaft closely, and the end surfaces of the graphite seal loop and the rotor shaft are tightly combined flexibly. A method for sealing the turbine booster includes: sealing a compressor, putting a prepared V-type rubber seal loop on an outer jacket in the cover base and binding the end surfaces of them closely and combining the surfaces of them flexibly by a low pressure spring and a spring baffle piece.