The basic principle of the multiblock method is to split a computational domain into several smaller ones. It is frequently used to deal with complex geometry and in parallel computing. The basic multiblock method is described including the way of splitting and the interface conditions in matching solutions between adjacent subdomains. Then we describe how to use the multiblock method to do parallel computing and how to analyze stability, convergence, conservation and uniqueness. Finally, an overview on stability, accuracy, convergence, conservation and uniqueness of a multiblock method is given.