We used a new hydrate separation method to recover C3H8 and C3H6 (C-3) from a butyl alcoholoctyl alcohol vent gas (BVG) mixture. The formation conditions of the BVG hydrate, which are crucial for the separating and operating conditions of C-3 recovery by hydrate formation, were measured by pressure search method at varied temperature. Then, the separation experiment was performed in a tap-water system at 274.15 K, and C-3 was recovered via hydrate formation in the presence of tetrahydrofuran (THF) and sodium dodecyl sulfate (SDS). The influences of experimental pressure and temperature on separation results were investigated. The total concentration of C-3 in the hydrated gas was 84.40 mol %, and the total recovery yield exceeded 80%. Therefore, the recovery of C-3 components from the BVG mixture through hydrate formation at a low pressure is a feasible strategy.