Have been to the United States, you can simplify the materials when applying for a Canadian visa, just provide:
1, original passport
2.2 photos
3. Copy of ID card
4. Original statement of detailed current account in the last 6 months.
5. Original employment certificate
6. Copy of business license or organization code certificate
7. Application form: application form for temporary residents' visit visa (IMM5257E), family information form (IMM5645E), education and employment details form.