The invention discloses a novel solvent for dissolving chitin by a freezing-unfreezing method or a direct dissolving method, and a use of the solvent composition. The solvent is a KOH aqueous solution, and further comprises any combination of LiOH, NaOH, urea or thiourea. The chitin and the solvent are mixed and then frozen to a point lower than a freezing point, and unfrozen at a point higher than the freezing point to obtain the chitin solution; or, the solvent is pre-cooled to the freezing point of 0 DEG C, and then the chitin is added to the cooled solvent for continuous stirring for more than 3 minutes, so that the chitin is quickly dissolved to form a transparent chitin solution. The chitin solution prepared in the invention can be processed into a chitin finished product of any form, for example, a film type, a plate type, a tubular type, a block type, a granulate type and a fiber type, and further can be processed into various chitin derivatives. The solvent composition is suitable for large-scale popularization and application.