They began the match making their intent known as Charlie Swannick burst through the defensive line to dot down for the opening try within the first two minutes.
Harry Pryer, Ed King and Freddie Gander (twice) followed suit throughout the first half, sealing the bonus point.
The second half remained a one-sided affair as Adejimi George-Coker set the scoring off inside the opening two minutes.
The tries continued to flow as Lewes managed to find a higher gear. The scoring continued with Tom Petty, Gav Hutt and Edd Lawrence closing out the scoring.
This win puts Lewes just three points shy of current league leaders St Francis, which leaves the final match against Burgess Hill II on April 16 as an important match, when a win will make them league champions.
Meanwhile, next door the 1st XV, missing out on many key players, found it harder going in a cup game against Eastbourne.
With seven changes in the side, they began in a rather disjointed manner and had conceded forty points by half time.
They did though manage one try in response when a driving maul propelled the Lewes forwards over the line for a try by skipper, Elliot Moule. Whatever was said to the Lewes players at half time, they came strongly out of the blocks as the second half began, with much more cohesion in their play, and totally dominated the third quarter. Joe Reid and George Gribble scored tries, before Eastbourne came back into the game in the final quarter to seal their 64-15 victory.
Heathfield duly collected the bonus point win the respective league positions suggested but there was a massive difference between the first 22 minutes and the rest of the match.
Heathfield scored five tries in that time but just one thereafter. The first few minutes were incident-packed. Crawley kicked for touch after securing possession from kick-off but were outside their 22. From the lineout Heathfield quickly worked through several phases leading to Ed Koops charging over for the opening score.
Crawley soon regained possession and worked the ball left but Sam Williams intercepted near his own 22 and had too much pace.
Heathfield were playing with clinical intensity and tempo so it was no surprise when Williams again outran his opponents to touch down in the corner, 0-19 after just eight minutes.
The bonus point try arrived after 15 minutes as a home lineout was turned over and good hands across the pitch with a significant contribution by Toby Simpson put Sean Crozier in for the try.
A handy run by Liam Dunkley led to Tom Pritchard finishing the move from 20 yards out.Remarkably there was just one score by each side thereafter.
The spark had gone out of Heathfield’s play but a score did finally come approaching the final quarter when Archie Adams beat a couple of opponents in the corner to jog behind the posts to touch down.
Tom Cornwall took a yellow card and Crawley scored a try from short range.
Heathfield finish in fourth in the league.