Some physiological-biochemical characters were investigated when sweet pepper potting seedlings were exposed to different degree water stress and rewatering. The main results were as follows: the lower RWC in media, the lower osmotic potential and saturated osmotic potential, but the higher osmotic adjustment and injury degree as well. The activity of POD、SOD、CAT increased with the decreasing moisture content. Of the above three defense enzymes, SOD was the most sensitive to water stress. Whereas after rewatering, probably it was POD and CAT that were mainly responsible for eliminating H2O2 and peroxides. Free amino acid and proline could principally play osmotic role under earlier light stress, accumulating sharply under water stress, yet rapidly reduced after rewatering. Soluble protein and soluble sugar obviously accumulated until RWC reduced to 45%, a little later than amino acid, and that they seemed to play osmotic role when relatively serious stress during later period. Although water stress could make protective enzymes activity and osmotic adjustment promote, but any stress would inevitably damage seedlings. Therefore, considering long-distance transportation and high-quality seedlings production, 2~3days stress hardening was more appropriate.