The invention discloses a coal gas surface filling device applicable to a model test. The coal gas surface filling device comprises an inflation panel, wherein one end of the inflation panel is connected with an inflation pipeline; an inflation switch is arranged on the inflation pipeline; the inflation panel comprises a panel; the panel is provided with gas guide grooves which are vertically and horizontally crossed and communicated; the gas guide grooves are communicated with the inflation pipeline through an inflation channel at the end part of the panel; a lower sieve plate, a steel wire gauze and an upper sieve plate are orderly arranged on the panel; the edge joint of the lower sieve plate, the steel wire gauze, the upper sieve plate and the panel is sealed by a rubber sealing strip; a fixed pressing strip is arranged on the edge of the sieve plate, and the lower sieve plate, the steel wire gauze and the upper sieve plate are fixed on the panel through bolts. The coal gas surface filling device can carry out large-area uniform and fast gas filling on a test coal seam, has good gas permeability and boundary binding character, can filter fine pulverized coal, and does not destroy the model or leak air from the side; the flow and pressure are adjustable; the safety is high; the structure is simple; the performance is excellent; the price is low, and maintenance and exchange are convenient.