The 25-year-old South African, the 100m, 200m and 400m Beijing Paralympic champion, recorded a time of 45.20 seconds in winning the 400m at the Provincial Championships for Gauteng North in the selection event for his country's National Championships.
That time was inside the Olympic qualification standard of 45.30secs.
Pistorious, who runs with carbon fibre prosthetic running blades after being born without a fibula in both legs, also clocked 45.07s last July in Lignano to qualify for last summer's World Championships in Daegu.
Pistorious, who still has to earn selection for the South Africa Olympic squad, said: "I am absolutely thrilled to have run the Olympic qualification time . This is a huge moment for me and I am trying to take it all in.
"The race went well and the conditions were perfect - I could feel every step of the way that my race plan was in motion, I felt strong out there and when I crossed the line and saw the time it was such a magical moment for me.
"I am looking forward to hopefully being confirmed by SASCOC (South African Sports Confederation and Olympic Committee) as a member of the South African Olympic team and I will do everything I can to train and prepare to the best of my ability and I would be proud to compete for my country at the Olympic and Paralympic Games."