Nowadays, one of the biggest challenges of education in Thailand is the development and promotion of the students' thinking skills. The main purposes of this research were to develop an analytical thinking test for 6th grade students and evaluate the students' analytical thinking. The sample was composed of 3,567 6th grade students in 2014 academic year at schools in Samuthsakorn province, the largest sample size that has been reached so far for an analytical thinking test in Thailand. The instruments for collecting data were the analytical thinking skill test; Fact vs. Opinion test (F vs. O test) and Ordinary National Educational based test (O-NET based test). The collected data were analysed through TAP 6.65, SIA1.0.1 and SPSS 22 statistical programs. The results revealed statistic consistency between F vs. O test and O-NET based test. In addition, most 6th grade students were in "Unsatisfactory" level for analytical thinking skills. Though improvements are much needed, we believe that the developed Fact vs. Opinion test suits for the promotion and evaluation of the students' analytical thinking skills.