The purpose of this study was to explore professional autonomy, nurse work environment, clinical decision making ability and identify factors that affect clinical decision making ability of clinical nurses.
The subjects of this study were 263 nurses from general hospitals in D city. The data was collected from July 1 to 15, 2011 using the self report questionnaires. The data were analyzed using descriptive statistics, t-test, ANOVA, Pearson''s correlation coefficient and hierarchical multiple regression by SPSS WIN 20.0 program.

The results were as follows :
1. The mean score of professional autonomy, nurse work environment in the work and clinical decision making abilities of clinical nurse were 160.3, 22.2 and 128.2 respectively.
2. Clinical decision making ability was significant difference by marital status, special nurse certification, career, satisfaction job.
3. A positive correlation was found between professional autonomy, nurse work environment and clinical decision making ability.
4. In multiple regression analysis, factors influencing on clinical decision making ability were marital status, professional autonomy and nurse work environment. The strongest predictor of clinical decision making ability was nurse work environment. In addition, marital status, professional autonomy and nurse work environment accounted for 25% of variance in clinical decision making ability.

The results of the study show that professional autonomy and nurse work environment are important predictors of clinical decision making ability of clinical nurses. Therefore it is recommend that decision making ability training programs for clinical nurses be develop to enhance their professional autonomy and clinical decision making ability. And it is necessary to construct and serve nurse work environments to promote clinical nurses'' autonomy and satisfaction with job.