The purpose of this study was to investigate the probable effects of cognitive in linguistics properties of descriptive writing. The cognitive was studied on reflectivity and impulsivity in which students were categorized in to two groups. The linguistics properties of the learners' descriptive writings were examined through syntactic complexity under syntax studies umbrella. The participants were selected from systematic random sampling technique and by applying the personality test subjected degree of cognitive level from Eysenck Personality Questionnaire (30 from the most reflective learners and 30 from the most impulsive learners). The selected participants were asked to write descriptive essay about person. Syntactic complexity (simple, compound, complex and compound-complex) was calculated from each of learners' writing and the significant difference between two groups were analyzed by employing the independent sample t - test in SPSS version 21. The result shows that there were differences between reflective and impulsive learners in producing syntactic complexity in descriptive writing. Even though, there were differences on syntactic complexity, the assumption of teachers on, impulsive learners are better than reflective students, does not suit to the linguistics properties competencies and performances especially on syntactic complexity of the descriptive writing because both of them had their own superiority in syntactic complexity.