A valve mechanism, comprising: a valve having a valve roller; a camshaft provided with a cam; an intermediate swing arm located between the cam and the valve, the cam driving the valve to move by means of the intermediate swing arm swinging around an intermediate swing arm shaft, characterized in that the valve mechanism comprises: a fixed support comprising a fixed portion and a connecting portion, the connecting portion being connected with the fixed portion, and provided with a connecting-portion via hole running from top to bottom, and the connection portion defining an oil passage therein, the intermediate swing arm being mounted in the fixed portion, and the oil passage being connected with the connecting-portion via hole and configured to output lubricating oil to the intermediate swing arm shaft; and a supporting base comprising a base body and a base-body camshaft supporting portion configured to support the camshaft; wherein the supporting base defines a first supporting-base oil feeding passage and a second supporting-base oil feeding passage therein, the first supporting-base oil feeding passage is communicated with the connecting-portion via hole, and an upper end of the second supporting-base oil feeding passage extends to the base-body camshaft supporting portion, so as to output the lubricating oil to the camshaft. a valve having a valve roller; a camshaft provided with a cam; an intermediate swing arm located between the cam and the valve, the cam driving the valve to move by means of the intermediate swing arm swinging around an intermediate swing arm shaft, characterized in that the valve mechanism comprises: a fixed support comprising a fixed portion and a connecting portion, the connecting portion being connected with the fixed portion, and provided with a connecting-portion via hole running from top to bottom, and the connection portion defining an oil passage therein, the intermediate swing arm being mounted in the fixed portion, and the oil passage being connected with the connecting-portion via hole and configured to output lubricating oil to the intermediate swing arm shaft; and a supporting base comprising a base body and a base-body camshaft supporting portion configured to support the camshaft; wherein the supporting base defines a first supporting-base oil feeding passage and a second supporting-base oil feeding passage therein, the first supporting-base oil feeding passage is communicated with the connecting-portion via hole, and an upper end of the second supporting-base oil feeding passage extends to the base-body camshaft supporting portion, so as to output the lubricating oil to the camshaft. a fixed support comprising a fixed portion and a connecting portion, the connecting portion being connected with the fixed portion, and provided with a connecting-portion via hole running from top to bottom, and the connection portion defining an oil passage therein, the intermediate swing arm being mounted in the fixed portion, and the oil passage being connected with the connecting-portion via hole and configured to output lubricating oil to the intermediate swing arm shaft; and a supporting base comprising a base body and a base-body camshaft supporting portion configured to support the camshaft; wherein the supporting base defines a first supporting-base oil feeding passage and a second supporting-base oil feeding passage therein, the first supporting-base oil feeding passage is communicated with the connecting-portion via hole, and an upper end of the second supporting-base oil feeding passage extends to the base-body camshaft supporting portion, so as to output the lubricating oil to the camshaft.