Electric Circuits is one of mandatory courses in electrical engineering. This course consists of basic electronic components, modeling concept and circuit analysis in direct current (DC) or alternating current (AC) which are fundamental for varies advance courses. However, this course gives a significant contribution to student's failure at every term. The data, from last term, show that 16.02% of 256 students got D, E and T (DET) grade. That is exceed 15%, a standard set by Telkom University. This research proposes a fusion method between Learning Together method (LT) and software (LTSPICE) simulation. LT method's aim is to leveling knowledge for each student meanwhile software simulation's is to give a better understanding for students and verify their work. The purpose of this research is to find a suitable learning method which can reduce DET index and to increase student's achievement in electric circuits course at Telkom University. This research is an action research which is designed in two cycles. Each cycle consists of four steps: Planning, Acting, Observing and Reflecting. The research data are obtained from observation form, assignment and exam results (pretest and posttest). These results showed that the proposed method can increase student's achievement about 3% in final exam compared with a mid-term exam and it successfully decreased DET index about 5% compared to previous term results.