In order to study the fundamental physical mechanisms of fluid flow and heat transfer in microchannels, many effects should be taken into account. The effect of axial heat conduction on heat transfer in microchannels is one of the hottest topics. Experimental investigation was carried out to analyze heat transfer characteristics of methanol flowing through microchannel heat sink, which consists of 10 parallel triangular microchannels. Experimental results show that the temperature distribution on the heated wall do not change linearly along the channel, which mainly caused by the axial heat conduction in the wall. The ratio of the power due to the axial heat flux to the Joule heating in the heater, and the axial heat conduction number were used to evaluate the heat conduction effect in the wall. Many factors play important roles in the axial heat conduction, including geometric configuration, material of the wall, and Reynolds number. The experimental study reveals that the axial heat conduction effect is gradually strengthened as the Reynolds number decreases.