Arylpyrazoline microparticles dispersed in water are synthesized and their absorption spectra are compared with those in solution. It is found that the absorbance of pyrazoline group in solution of 5-aryl arylpyrazoline is far greater than that in solution of arylpyrazolines with no 5-aryl group. This hyperchromic effect is intensified in 5-aryl arylpyrazoline microparticles. It is indicated that intramolecular charge transfer exists between pyrazoline group and 5-aryl group and this kind of interaction is increased in their microparticles.