Abstract: Based on the surface tension of curved liquid surface，the capillarity in triangular capillary is studied. Using Matlab numerical simulation，the surface tensions of two kinds for liquid surface with different contact angle functions，the height and velocity of liquid in the capillaries are calculated. The results show that as the same caliber，the height in triangular capillary is larger than that in circular capillary. Considering the impact of friction f = 1.732×10-2y N the velocity of liquid in capillary is consistent with the actual situation.

Key words: capillarity, surface tension, triangular capillary, velocity