Tries from Josh Bainbridge, two from Rotimi Segun, two from Kai Little, Cameron Cowell, Jack Stanley, Taylor Prell, Harry Mallinder and Joe Marchant gave England the win, while Mallinder also added 12 points with the boot.
After a cagey opening five minutes, in which Portugal more than held their own, England's forward power eventually told and Bainbridge touched down after a rolling maul.
Wing Segun then scored twice in quick succession, showing good acceleration out wide before touching down.
England looked dangerous the ball in hand and had two more tries before half time - Kai Little scored both to make it 29-0 after a Mallinder conversion.
Portugal grabbed their only try of the match just before the break, and it was a while before England had their sixth. It eventually came from Cowell who showed good pace before darting over for his first England try.
Stanley then bulldozed over before Prell got himself on the end of a lovely team move for England's seventh and eighth tries.
Mallinder spotted a gap through the middle to score before Marchant rounded things off at the death to make it 62-5.
Points: Bainbridge 1T, Segun 2T, Little 2T, Cowell 1T, Stanley 1T, Prell 1T, Mallinder 1T, Marchant 1T; Mallinder 6C
15 Cameron Cowell (St Pauls Catholic College, London Irish)
14 Kai Little (Hartpury College, Exeter Chiefs)
13 Joe Marchant (Peter Symonds, Harlequins)
12 Harry Mallinder (Rugby School, Northampton Saints)
11 Rotimi Segun (Stowe School, Northampton Saints)
10 Theo Brophy-Clews (Abingdon School, London Irish)
9 Alex Mitchell (Lymm High School, Sale Sharks)
1 Owen Hills (Queen Elizabeth Wyggeston College, Leicester Tigers)
2 James Fish (Trent College, Northampton Saints)
3 Josh Ibuanokpe (Dulwich College, Harlequins)
4 Huw Taylor (Old Swinford Hospital, Worcester Warriors)
5 Stanley South (Whitgift School, Harlequins)
6 Joe Batley (Hartpury College, Gloucester Rugby)
7 Josh Bainbridge (Prince Henry's Grammar, Leeds Carnegie)
8 Callum Chick (Gosforth Academy, Newcastle Falcons)
16 Ollie Adams (St Pauls Catholic College, London Irish) on for James Fish 46 mins
17 Lewis Boyce (Prince Henry's Grammar, Leeds Carnegie) on for Owen Hills 46 mins
18 Jack Stanley (Truro College, Exeter Chiefs) on for Josh Ibuanokpe 35 mins
19 George Nott (Kings School Chester, Sale Sharks)
20 Will Safe (Hartpury College, Gloucester Rugby) on for Joe Batley (42 mins)
21 Sam Underhill (Sir Thomas Rich's School, Gloucester Rugby) on for Josh Bainbridge 56 mins
22 Jack Maunder (Blundells School, Exeter Chiefs) on for Alex Mitchell 50 mins
23 Charlie Thacker (Leicester Grammar, Leicester Tigers) on for Theo Brophy-Clews 60 mins
24 Lucas Slowik (Filton College, Bristol Rugby)
25 Taylor Prell (Giggleswick School, Leeds Carnegie) on for Kai Little 50 mins