The invention discloses an intensive biomass pyrolysis gasification fuel gas purifying device which comprises a comprehensive absorption tower and a comprehensive separation tower, wherein the comprehensive absorption tower comprises a water cooling tower (1) at the lower part and an alkali spray tower (2) at the upper part, wherein the comprehensive separation tower comprises a gas-liquid separation tower (14) at the lower part and an adsorption tower (15) at the upper part; a water-cooled heat exchanger is arranged in the water cooling tower (1), and a tube plate net (8) is arranged at the upper part of the water cooling tower (1); and downward spiral-flow plates (20) are symmetrically arranged from top to bottom in the gas-liquid separation tower (14). By combining two tower, the functions of the two towers are integrated on one tower, and miniaturization and intensification of a biomass combustible gas purifying device are realized; and moreover, a relatively good purifying effect can be realized, and the investment cost and operation/maintenance cost are reduced.