This study aims to improve students' ability to write descriptive texts and think critically through task-based learning methods at SMA N 1 Sungai Ambawang. In this study the researcher tried to find out the role of task-based learning in improving the students writing and critical thinking. This participant on this study are the students of class X IPA 1.
The researcher used the observation technique to collect qualitative data including watching and considering the unconstrained behavior of members in an open or common environment and the researcher used tests to measure writing
and critical thinking skills. The tool of data collection used the field notes to record activities during the research process. Researcher used tests to measure students' abilities in writing descriptive texts and critical thinking. The data analysis used in this study is a mixed-method to combine quantitative and qualitative data. Theoretically, the researcher uses three theories, all of which explain the task-based learning method.
This study shows some students are interested in using task-based learning methods, which significant improvement in each cycle where mean score in the first cycle was 63,33% (written test), 50.67% (critical thinking test) that categorized into average and the second cycle was 82.33% (written test) 74% (critical thinking test) to improve students writing and critical thinking skills seen from the results of the value obtained through the test during this study conducted. Based on the results of this study, it can be concluded that the task�based learning method can stimulate students in improving their ability to write
descriptive texts and think critically. In this study, the researcher suggests readers take lessons in this research as a basis for developing more interesting learning methods in the future.

Keywords: A Classroom Action Research, Task-Based Learning Method, Writing, Critical Thinking, Descriptive text