Mounties say the provincial sheriff had been standing outside, checking on motorists involved in another crash in Red Deer on Highway 2, when he was hurt.
An out-of-control semi truck jackknifed and slid into both the officer and his cruiser.
The man was taken to Red Deer hospital by ambulance and treated for serious but non-life threatening injuries.
Snowfall and travel warnings were issued Thursday throughout the province.
RCMP said Highway 2, the main road linking Edmonton and Calgary, was especially slippery and blowing snow caused poor visibility in several areas, prompting them to warn against travel.
Cpl. Darrin Turnbull, a spokesman with the traffic unit that patrols Highway 2, said officers were kept busy Thursday going from one crash to the next.
"If there was nobody injured, they weren't even staying to document the collision. They were moving on to the next collision. There were so many collisions in so many locations all the way, from Calgary to Edmonton."