Control chart is a common tool of quality control. Control chart can be viewed as a coverage interval, with a certain coverage probability. In this article, we reconstruct control chart from statistical point of view, and categorize them into population-type control chart and sample-type control chart. We study on X − S chart under normal distribution and exponential distribution, and also on individuals control charts under normal distribution. In addition, we construct confidence intervals of control charts and compute their coverage probability. Traditional process control actually tests if the process mean of a control chart is changed. The confidence interval of a control chart expands this hypothesis testing to test if the control chart interval is changed.