This monograph is based on my research work in pulsar astronomy, in which Chapters 3, 4, 6, 8, and 9 are mainly based on the previous works that need to be interpreted more deeply with the current progress in the relevant areas of the subjects. I hope this work will provide more insights about the state-switching of intermittent pulsars and the corresponding change in the pulsar magnetosphere. The link to the original paper is given under each chapter for convenience. I believe this monograph may have many defects and shortcomings. Any comments or suggestions are highly appreciated.