The invention discloses a pediatric clinical diagnostic apparatus which comprises a diagnostic mechanism and a spacing adjusting mechanism, and the spacing adjusting mechanism is arranged on the diagnostic mechanism. According to the spacing adjusting mechanism, the doctor selects an inner threaded hole with a proper height to adjust the distance between auditory tubes to a proper position, a protective sleeve is arranged at the joint of a sound guide tube and a branch tube, the joint is effectively prevented from being broken, the service life is prolonged, a heating assembly is arranged on an auscultation sensor, the situation that the auscultation sensor is used at a low temperature, and discomfort of children is increased is avoided, the outer sides of the earplugs are provided with the sealing earmuffs, the listening accuracy of a doctor is guaranteed, interference of external noise is prevented, cartoon patterns are arranged on the outer sides of the sound guide tube and the branch tube, attention of a child during diagnosis is distracted, anxiety and panic of the child when the doctor uses the diagnostic instrument are prevented, the head fixing assembly is arranged on the auditory tube, the diagnostic instrument is convenient to fix, and, in addition, the elastic band can be conveniently cleaned and replaced.