The hyperbranched polytriazole (hb-PTA) containing second-order nonlinear optical chromophore was synthesized through "A(2) + B-3" approach based on "click reaction." Its corresponding linear analogue (I-PTA) was prepared for comparison. The hb-PTA has better solubility in common organic solvents than the I-PTA. Both the polymers exhibit good thermal stability with 5% weight loss temperatures over 260 degrees C. The poled film of hb-PTA exhibits much higher second-harmonic coefficient (96.8 pm/V) than that of l-PTA (23.5 pm/V). The three-dimensional spatial isolation effect resulting from the highly branched structure and the crosslinking of the terminal acetylene groups at moderate temperature play important roles in the enhancement of optical nonlinearity. (c) 2008 Wiley Periodicals, Inc.