Objective   In order to know the influence of passive smoking on children's respiratory system diseases, concentration of sulphocyanate in saliva, non-specifical immunity.

  Methods   The smoking state of children's family members and health condition of 1031 children aged 4-6 years in 4 kindergartens which condition and source of children were similar were investigated with selfmade questionnaire; the height and weight of children were measured and the sulphocyanate, bacteriolytic enzyme and immunoglobin (IgG, IgA, IgM)in saliva of children were examined.

  Results   (1) The quantity of passive smoking were positive related with concentration of sulphocyanate and negative related with concentration bacteriolytic enzyme in saliva; (2)the concentration of immunoglobin (IgG, IgA, IgM)in saliva were decreased with the increasing of quantity of passive smoking; (3)the proportion of children suffered from respiratory system diseases ≥4 times and cold ≥4 times in a year were increased upon the increasing of quantity of passive smoking, the quantity of passive smoking were positive related with times of suffering from respiratory system diseases in a year; (4) the height and weight of children were decreased with the increasing of quantity of passive smokiog, the quantity of passive smoking was negative correlative to height and weight, especifily for the younger.

  Conclusion   Passive smoking can influence the children's non-specifical immune function and height and weight which was detrimental to health of children.