Lee Yunri from the Republic of Korea, who won gold at Beijing 2008, could only manage 668.6 points to finish fourth.
Zhang won the first gold medal of London 2012 when she collected the title in the women's R2-10m Air Rifle Standing - SH1, before following up with bronze in the Mixed R3-10m Air Rifle Prone - SH1.
Following her latest triumph, Zhang said: 'I was very, very nervous. But after my poor first shot, I became very calm so I got better and better in the following shots.'
In the Mixed P4-50m Pistol - SH1, defending champion Park Seakyun produced a superb performance to reclaim his title.
The Republic of Korea shooter delivered a strong closing series, producing final shots of 10.4 and 10.3 to win with a total of 642.4 points.
It marked his second gold medal of London 2012 after victory in the men's P1-10m Air Pistol - SH1.
He said: 'I was so nervous. This match is really meaningful to me as now I have won two golds.'
Russian Valery Ponomarenko took silver with 633.2 points while Ni Hedong of China shot to bronze (625.3).