去你居住地附近的加拿大使领馆申请.
比如关于在北京使馆如何申请，请参阅
http://www.canadainternational.gc.ca/china-chine/consular_services_consulaires/beijing-pekin/passport-passeport.aspx?lang=eng
注意下半部分“Passports for Children Under the Age of 16”中提到：
Note: If a child is born abroad and has not yet obtained a certificate of Canadian citizenship, parents must submit the citizenship application prior to the passport application.
也就是父母都是加拿大国籍，孩子出生在中国，也是凯指加拿大国籍，但要先申请“certificate of Canadian citizenship”，然后才能申请盯禅配护照。当然你说的“现在小孩子也是加袭升拿大国籍的”如果是孩子已经申请领到“certificate of Canadian citizenship”了，那就可以直接按程序申请护照了。