A longitudinal study on vocal pitch matching abilities, pitch discrimination abilities, and skills at the separation of a singing voice from a speaking voice of four years old children (n = 34) was conducted to explore children's vocal pitch accuracies in singing, and associated abilities and skills. The children were investigated four times half-yearly. first and second time's investigations were conducted when the children were four years old, and third and fourth time's investigations were conducted when the children were five years old. The following results were obtained: (1) The children significantly developed vocal pitch matching abilities from first time's investigation to second time's investigation. Then, the children developed into a middle level of vocal pitch matching abilities. Their developments may be associated with the developments of pitch discrimination abilities. (2) The developments into a high level of vocal pitch matching abilities advanced gradually. There weren't high percentages of children with the level 4 of vocal pitch matching abilities in fourth time's investigation. Infants may not develop vocal pitch accuracies in singing sufficiently. Their developments may be associated with the developments of skills at the separation of a singing voice from a speaking voice.