Cook rice in microwave as directed on package. Place in bowl; cover to keep warm.
In 12-inch skillet, heat oil over high heat. Add onion; cook 1 minute, stirring frequently. Add bell peppers; cook 3 minutes, stirring frequently.
Stir in shrimp and pineapple. Cook 3 minutes, stirring frequently. Reduce heat; stir in sweet-and-sour sauce. Cook 1 to 2 minute, stirring constantly, until shrimp are pink. Serve shrimp mixture over rice.