Objective To study the T/P rate and smoothness index of Candesartan Cliexetil on slight and middle essential hypertension. Methods 50 patients with slight and middle essential hypertension were treated by Candesartan Cliexetil 8mg taken orally everyday,the course of treatment was 4 weeks. 24h ambulatory blood pressure monitoring(ABPM) was given before and after treatment, the T/P rate and smoothness index were calculated. Results Four weeks after treatment, 24h SBP(148.2±10.7) mm Hg and 24 h D BP (97.6±6.5) mm Hg, dSBP(152.5±9.8) mm Hg and dDBP(96.0±5.3) mm Hg, nSBP(138.3±7.6) mm Hg and nDBP(89.2±8.3) mm Hg, SBP load (87.5±12.2) % and DBP load (36.48±26.4) % with pre-treatment (130.2±7.2) mm Hg, (79.5±7.8) mm Hg, (133.4±7.2)mm Hg, (81.8±6.6)mm Hg,(121.9±7.3) mm Hg, (72.1±7.4) mm Hg, (84.7±9.9)%,(26.7 ±8.3) % have significant difference(P < 0.01). T/P rates were SBP 70% and DBP 63%. Smoothness indexes were SBP(1.21±0.82) and DBP(1.13±0.51). Conclusion Candesartan cilexetil in the treatment of essential hyper-tension is safe and effective,can get a good T/P ratio and smoothness index.