Two goals from Ronan Curtis and one from Jamal Lowe kept up the Blues' flying start to the season.
Here's what some key figures had to say after the game.
Pompey boss Kenny Jackett
It was a great performance. I thought we were excellent. We controlled the game for 35 minutes and perhaps then lost our way a bit.
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But we defended very well with our centre-halves and an important take or two from the keeper. We lost three to injury in the first half, but the players coming on were as good as the ones going off. That’s good for us.
Then we went further away in the second half and deserved the win.
Blues defender Nathan Thompson
We set our stall out early, were dominant from the start. You look at a Plymouth team coming off the back of a 5-1 defeat last weekend and confidence is saturated a little bit – you could see that as soon as we scored the second goal.
I thought dealt with the atmosphere and were cool and collected, it was a good performance. They had a 10-minute period just before half-time when they got their tails up and we took off Hawks (Oli Hawkins) and it slowed the tempo of the game, so they got back into it.
That is why it was important to start the second half strongly – and I thought the boys did that. It was a matter of then controlling it and taking our opportunities, which we did.
The News' Neil Allen
Pompey produced a confident display to overwhelm Plymouth at Fratton Park.
With Ronan Curtis the inspiration, Kenny Jackett's men were streets ahead of the struggling visitors, fairly reflected by the scoreline.
It maintains the Blues' encouraging start to the campaign - and strengthens promotion credentials which are all-too obvious.
The News' Jordan Cross
It was a perfect day for Pompey as they showcased their promotion potential by sweeping aside Plymouth in the Fratton Park sunshine. There was much to admire about Kenny Jackett's side as they kept up their unbeaten league start.
There was the manner in which the Blues counter-attacked in numbers and opened up the visitors with pace on break. And that melded perfectly with their defensive resolve as they picked up their second clean sheet on the bounce, with three goals conceded in six league games. It may be early days, but things are shaping up promisingly.
Chris Errington of cornwalllive.com
Plymouth Argyle’s defensive frailties were there for all to see as Portsmouth despatched them with some ease at Fratton Park. It was a third successive defeat for the Pilgrims in all competitions and they have conceded 10 goals in the process.
For a team which has usually been so strong defensively under the management of Derek Adams that is very alarming. It was a familiar story of the opposition being able to put too many crosses into the penalty area unchallenged. Possession was also given away too often and that allowed Portsmouth to launch pacy attacking raids.