The invention discloses carboxymethyl starch sodium oral solution and a preparation method thereof; the carboxymethyl starch sodium oral solution mainly contains the following components of: carboxymethyl starch sodium raw material medicine, a sweetening agent, a flavor agent, a metal chelating agent, and a pH regulating agent; in clinical practice, the carboxymethyl starch sodium oral solution can be widely used for the treatment of children recurrent respiratory tract infection due to low immunity and induced bronchitis and asthma thereby.