A late recovery enabled Brentford to extend their unbeaten start to the season after they had looked well beaten.
Notts remain without a home win after three attempts.
County made tactical switches when Marcel Cas was ruled out by injury. With no other wide players, manager Bill Dearden withdrew striker Mark Stallard to play behind the front pair of the Daniel Allsopp and Paul Heffernan and used Darren Caskey in a deeper role.
It worked like a charm and Notts were ahead inside ten minutes with a cool piece of Stallard finishing, his first Meadow Lane goal in 11 months.
Heffernan should have added a second but his control let him down but two minutes into the second half he atoned by rounding off a fine a piece of play between Allsopp and Stallard.
By then Notts could have been three ahead, Kevin Nicholson having rattled the crossbar.
Brentford battled on and Leo Roget forced a fine save from Stewart Garden before the Notts goalkeeper was undone by two clinical finishes by the visitors.
Mark McCammon shrugged off Craig Ireland's challenge to reduce the arrears after 56 minutes and substitute Mark Williams levelled 12 minutes from the finish after good work by Rowan Vine, this time Danny Stone being the culpable defender.
Magpies manager Dearden was critical of his defenders for losing their shape - and almost the match in the closing stages.
He described the refereeing performance by Barrow-in-Furness official Mike Pike as one of the worst he had ever seen in a long football career.
Dearden was pleased with the way his new formation had operated but clearly the frustrations are growing at County's inability to win at home