This thesis aims to describe 1) whether and to what extent the optimizing of Mind Mapping can improve students’ thinking skill in reading comprehension; 2) the difficulties of the implementation of Mind Mapping to improve students’ thinking skill in reading comprehension.
This action research is conducted collaboratively with one of reading lecturer of IKIP PGRI Madiun, in 4A class. This action research was carried out in two cycles which consist of planning, implementing, observing and reflecting. The qualitative data are collected using field notes, diary, questionnaire,interview and documentation. Then, the qualitative data are analyzed through data reduction, data display, and conclusion and verification .  The quantitative data are collected using test.  The test consists of pre-test and post test. The quantitative data are analyzed through descriptive statistics to compare the result of pre-test and post test.
The research findings show that Mind Mapping can improve students’ thinking skill in reading comprehension such as: 1) the mean score of the students’ thinking skill was increased from 80,7 to 96,6 and all of students’ scores were higher than the passing grade; 2) the total of students’ right answer of each thinking skill indicator was increased such as: part-whole relation from 192 to 228, conclusion from 141 to 192, similarities from 172 to 200 and differences from 181 to 203; 3) in the implementation of mind mapping, the students got some difficulties such as: the students were confused when they cannot find supporting statements in all of their articles, they were confused to choose the key words or shorten the sentences for the mind mapping step 3, and they were confused to put the key words in mind mapping step 3, It was quite difficult to find articles with the same topic but comes from different resources that consist of the same subtopics inside it as seen in the interview result in attachment, It was needed 2 meetings to do all the mind mapping process that means the mind mapping technique is time
consuming.  
From all of the findings, it can be concluded that Mind Mapping can improve the students’ thinking skill in reading comprehension. It can be seen from the students’ score improvement.In using Mind Mapping to improve the students’ thinking skill, the lecturer should let the student to find their own articles and provide the students a time to consult all their problems in doing the mind mapping.

Key words: Mind Mapping, thinking skill, reading comprehension, action research.