The associations of triblock copolymer made of acrylic acid, methyl acrylic acid and butyl acrylate in aqueous solution as well as in NaCl and CaCl 2 solutions were studied by using fluorescence. The micelle like clusters(MLCs) of copolymer formed is able to solubilize non polar material. A little electrolytes added in the copolymer solution can increase the value of critical aggregation concentration( ρ ac ) and micropolarity. But with the increase of the concentration of electrolytes, the value of ρ ac and micropolarity will decrease. When there is NaCl with fixed concentration in the systems, the process of the MLCs loosening is relaxed because of the charge screening. In the systems with fixed CaCl 2 concentration, Ca 2+ induced the cross link of -COO - groups, so the interface between the MLCs and the water is not obvious and the big MLCs is formed between the clusters.
