The sodium tetraphenylboron has the fluorescence quenching effect on rhodamine B, making the fluorescence signal intensity weaken or even disappear. But cetirizine dihydrochloride has the anti-quenching effect on rhodamine B--the fluorescence signal is enhanced, and there was a linear relationship between the fluorescence signal enhancement degree and drug concentration. In the present paper, 491 and 610 nm were chosen as the excitation and emission wavelength for measurement of the fluorescence intensity difference deltaF = F1 - F0 of blank solution and test solution, and according to positive correlation between the value of deltaF and cetirizine hydrochloride concentration of test solution, a new method of anti-fluorescence quenching for the determination of cetirizine hydrochloride was established. The linear regression equation was deltaF = 0.727 5m - 2.357, correlation coefficient was 0.997 2, linear range was 3.50-129.3 mg x L(-1), the detection limit was 1.05 mg x L(-1) and RSD was 1.2%. The cetirizine hydrochloride tablets and cetirizine hydrochloride capsules from different manufacturers were determined by this method, the measured values were basically in line with the labeled amount of drugs, and the recovery rate was between 92% and 106%.