As normal with friendlies Gary Issott gave a number of his team a chance to take part as changes were made when the visitors took the field for the second half.
Palace opened the scoring with a close range effort as an excellent cross from Mandela Egbo on the right to the back post was met by Sullay KaiKai, who headed home the first goal of the evening.
The lead was increased soon after, as Reise Allassani showed his pace to break away into the box and get the better of his marker to be in a position to shoot home past the 'keeper at the Eden Park Avenue ground.
Beckenham were back on level terms just before the break when a shot from outside the box was looped over David Gregory in the Palace goal and both sides went in at the break with a share of the spoils.
The summer sunshine was soon replaced by torrential rain as the second half got under way but it didn't stop the Palace youngsters as they wrapped up a comfortable victory on the night with two further goals.
Issott was happy with his sides first outing in a series of pre-season friendlies. "We got what we wanted, which was a good local game. It was a great turnout and hopefully it's raised some money for Beckenham; we've had a positive result and come through with no injuries and four goals.
"The idea was to give players 45 minutes each, then in the next two games 60s and 30s, and after that the majority of starting squad that will start the campaign 90 mins, but the idea was to give everyone an opportunity.
"Pre-season is tough for us. Havant and Waterlooville you could see in the 3rd round of FA Cup, Dulwich will be tough again, then we go to Forest Green. It will be a real test. With the first team being away, if the fans want to catch a game it will be fantastic."
1st half : Gregory, Egbo, Magri, Croll, Martin, Sow, Dymond, Allassani, De Silva, KaiKai, Ferrier.
2nd half: Gregory, Henry, O'Dwyer, Chambers, George, Gabsi, Sow, Black, Berkeley, Fehmi, Fizz.