The research aims to find out the effect of project-based science education programme conducted with an active learning on scientific process skills and conceptions of 6-year-old children about nature of science. Quasi-experimental research design including experimental and control groups with pre-test and post-test was implemented. Mixed-method research including qualitative and quantitative data collection tools was adopted. The quantitative data were collected with Preschool Scientific Process Skills Scale while qualitative data were gathered with interviews to define scientific process skills of children. The research includes 26 children in total, 17 were in the experimental group and 9 were in the control group. Project Based Science Education Conducted with Active Learning was carried out on the experimental group and Project Based Science Education was carried out on the control group. The research lasted for 32 weeks between October, 2015 and June, 2016. Scores of scientific process skills about nature of science belonging to students in the experimental group were found to be higher than ones in the control group and the students in the experimental group were found to be more familiar with the related conceptions. The findings prove the positive effect of project-based science education.