The purpose of this study was to study critical thinking skills of Hmong hilltribe students who were studying in seventh grade, in Tak province of Thailand. The research instrument used in this study was the critical thinking skills test developed by researcher. The test was a multiple-choice test which composed of 30 items with 30 total scores including three compositions of critical thinking skills ; 1) problem defining 2) decision making and data processing and 3) making conclusion. The participant in this study were 30 Hmong hilltribe students using purposive sampling who were studying in seventh grade in academic year 2015. The findings of the study revealed that the mean score of critical thinking skills of Hmong hilltribe students equaled 13.07. The maximum score was 20. The minimum score was 7 with the standard deviation 3.59. Moreover, the levels of critical thinking skills presented that 13.33% (n=4) of these students had critical thinking skills in a fair level, 23.33% (n=7) in a poor level and 63.33% (n=19) in a very poor level. In addition, considering separately in each composition of critical thinking skills, the results found that 60.24% of students got the right answers in decision making and data processing, 34.44% in problem defining and 25.67% in making conclusion, respectively.
