Preheat the oven to 350°F (175°C).
Mix crushed pretzels, melted butter, and sugar in a bowl.
Press the pretzel mixture into the bottom of a 9x13 inch baking dish.
Bake for 10 minutes, then let cool completely.
Beat cream cheese and powdered sugar until smooth.
Fold in whipped topping gently.
Spread the cream cheese mixture over the cooled pretzel crust.
Dissolve strawberry Jell-O in boiling water.
Stir in cold water and let it cool for about 10 minutes.
Pour the Jell-O mixture over the cream cheese layer and add sliced strawberries on top.
Refrigerate for at least 2 hours until set.