Objective　To explore the differences of teaching effectiveness between the tradi-tional experimental teaching method and the new one which is based on four steps of principle

design

correction and experiment. Method　Stratified sampling method was used

and 120 students were divided into control group and experimental group. Taking the case of the preparation of powder

the two methods mentioned above were used respectively. The advantage of the new teaching method was that teachers only explained the experimental principle rather than the detailed process

and students designed the process and quality control standard by reviewing literatures. Through interactive evalua-tion between teachers and students

teaching effectiveness of the two methods was evaluated

and Excel and SPSS were applied for statistical analysis. Result　There were no significant differences between the two groups in the aspects of experiment preparation

basic skills of experiment and understanding of knowledge (P>0.05)

but in the aspects of experiment initiative

degree of cooperation and the enthu-siasm of asking questions there existed significant differences(the values of P were 0.000、0.012、0.000，respectively

P<0.05). More than 95% of students thought the new teaching method not only could more effectively improve the ability to analyze and solve problem but also develop the capacity for self-learning and innovation. In addition

it could improve the ability to collect information and psychological quality

and cultivate scientific and rigorous attitude. Conclusion　Compared to the tra-ditional experimental teaching method

the new one based on four steps of principle

design

correction and experiment emphasized the subjective initiative

and teachers played a directive role. This method provided the space for students to think

explore

discover

and create. In addition

it could strengthen student's practical ability and the ability to design preparation process independently.