The　reduced　scale　experiments　were　conducted　to　investigate　the　LPG　flame　geometry　in　branched　tunnel　fire　under　different　airflow　velocities　to　better　comprehend　the　diffusion　flame　characteristics　in　narrow　-　long　space　with　multiple　entrance.　Five　different　heat　release　rates　varied　from　1.72　kW　to　5.18　kW　were　considered.　The　flame　tilt　angle　and　flame　length　were　measured　and　correlated.　Results　show　that　the　flame　tilts　downward　to　multiple　entrance　direction　(ramp　and　mainline)　under　natural　ventilation,　which　is　mainly　related　to　the　asymmetry　tunnel　cross-section　dimensions　between　fire　source　two　sides.　The　experiments　presented　three　different　flame　tilting　conditions　under　different　heat　release　rates　and　airflow　velocities　due　to　the　dominance　of　buoyancy　force　or　inertial　force.　The　flame　tilt　angle　is　correlated　using　the　nondimensional　heat　release　rate　and　Froude　number,　and　the　predictions　by　proposed　correlation　agree　reasonably　well　with　the　experimental　data.　The　flame　length　increases　with　the　heat　release　rate　and　elongated　by　airflow.　The　empirical　model　for　dimensionless　flame　length　are　developed　both　under　natural　and　longitudinal　ventilation.