Transportation is essential for people and goods to flow rapidly and easily. Bus system is one of the most dominant public transits and vital in Yangon. Performance measurements of public transits are important and useful to increase the quality of service and encourage the transit providers to fulfil the passengers’ needs. The study is in-depth analysis about the existing conditions of the (23) Blue and (23) Red bus lines from West Yangon Technological University (Hlaing Tharyar Township) to Tha Khin Mya Park (Ahlone Township). The performance of transit services such as reliability of arrival time, convenience and comfortable on the bus, facilities at bus stops and services on the buses are needed to be improved for passengers. Their quality of service components such as availability, comfort and convenience, reliability are analysed by Transit Capacity and Quality of Service Manual 3rd edition. Among them reliability is the most vital factor in service factor for the system to be successful from perspective of both passengers and operators. The results show that the service performance of reliability of two bus lines are decreased according to the irregular headways, , irregular headways with some bunching (level of service C), with some bunching (level of service D) and frequent bunching (level of service E). The facilities of each bus stop are analysed by the descriptive analysis. So, the requirement of service facilities should be improved in buses and at some bus stops. Furthermore, the study of passengers’ satisfaction of service quality of bus will be future work.