An international student is allowed to work in Canada depending on certain conditions like:
Working on Campus:
• you are a full-time student at:
• a public post-secondary institution, such as a college or university, or a collège d’enseignement général et professionnel (CEGEP) in Quebec or
• a private post-secondary institution that operates under the same rules and regulations as a public institution, and receives at least 50 per cent of its financing for its overall operations from government grants (currently only private college-level educational institutions in Quebec qualify) or
• a Canadian private institution authorized by provincial statute to confer degrees and
• you have a valid study permit.
Working Off Campus:
As of June 1, 2014, you may qualify to work off campus without a work permit. If you qualify, your study permit will allow you to:
• work up to 20 hours per week during regular academic sessions and
• work full-time during scheduled breaks, such as the winter and summer holidays or spring break.
To qualify, you must:
• have a valid study permit,
• be a full-time student,
• be enrolled at a designated learning institution at the post-secondary level or, in Quebec, a vocational program at the secondary level, and
• be studying in an academic, vocational or professional training program that leads to a degree, diploma or certificate that is at least six months in duration.
After completion of Studies a Student is allowed to stay back in Canada through POST GRADUATION WORK PERMIT PROGRAM.
To work in Canada after you graduate, you must apply for a work permit under the Post-Graduation Work Permit Program (PGWPP). If you want to stay in Canada as a permanent resident after you graduate, there are a number of programs available, each with its own requirements.

The PGWPP allows students who have graduated from a participating Canadian post-secondary institution to gain valuable Canadian work experience. Skilled Canadian work experience gained through the PGWPP helps graduates qualify for permanent residence in Canada through Express Entry.
A work permit under the PGWPP may be issued for the length of the study program, up to a maximum of three years. A post-graduation work permit cannot be valid for longer than the student’s study program, and the study program must be a minimum of eight months in length. For example, if you graduate from a four-year degree program, you could be eligible for a three-year work permit if you meet the criteria. If you graduate from an eight-month certificate program, you would be eligible for a work permit that is valid for no more than eight months.