Nim Gyeltshen is known for his expertise in Mask Dance at the Royal Academy of Performing Arts. He was appointed as Artist in the year 1985 and gradually promoted to the current post. He is an awardee of the National Certificate II & III in mask dance from the Ministry of Labour and Human Resources. He conducts training of trainers for the young aspirant trainees. He is well versed in Driglam Namzha and Dzongkha Unicode. With over 25 years of experience as a Mask dance instructor, he has participated in numerous Cultural programs such as Zhabdrung Ngawang Namgyel Zenam at Punakha (2004), Coronation of His Majesty the King (2008), Opera at El Paso, USA (2014) and various SAARC events. He also teaches mask dances to all twenty Dzongkhag dancers for their performance in the annual Tshechu. In addition to his primary responsibility, he is interested in sensitization of the importance of Bhutanese etiquette and chadri preparation works.