Customer satisfaction with library services has long been regarded as an important measure of library performance. Satisfying Users' needs in the public libraries should be the primary objective of libraries and librarians. This article introduces customers, customer demands, customer expectations, customer and perception; analyze customer complaint and the way to encourage customer complaints, the resolution of customer complaints and explores how to improve customer and workers' satisfaction. This article also introduces the experiences of Baltimore County Public Library and Taipei Public Library on satisfying Users' needs.