Mathematical proof is a logically formed argument based on students' thinking process. A mathematical proof is a formal process which needs the ability of analytical thinking to solve. However, researchers still find students who complete the mathematical proof process through intuitive thinking. Students who have studied mathematical proof in the early semester should not have completed abstract algebraic proof intuitively. Therefore, the aim of this research is to explore students' thinking process in conducting mathematical proof based on Mason's framework. The instrument used to collect data was mathematical proof problems test related to abstract algebra and interviews. There are three out of 25 students who did abstract algebra through intuitive thinking as they only used two stages of the Mason's thinking framework. Then, two out of three students were chosen as the subjects of the study. The selection of research subjects is based on the student's ability to express intuitive thinking verbally process which were conducted while completing the test. It is found that students can form structural-intuitive warrant that they use to complete the mathematical proof of abstract algebra. Structural-intuitive warrant formed by students at the stage of attack and review are in the form of: institutional warrant and evaluative warrant, while at the entry and attack stage are a priori warrant and empirical warrant.