The Omani emulated Tuesday’s bronze-medal winning performance in 100m T36 race with his second medal at the Games.
Harrasi capped his silver-medal victory with a personal best time of 59.75 seconds, losing the gold to Malaysia's Mohamad Ridzuan, who clocked 59.36s.
It was the second gold for Ridzuan, who had earlier beaten Harrasi in the 100m T36 race.
Iran's Farhad Kahrizi claimed the bronze in a time of 1m:00.39s.
Harrasi’s silver was Oman's third medal at the Games and it includes two silver and a bronze, all of them won in track and field events.
Oman's other medal winner was Mohammed al Mashaykhi, who had won a silver in the men's club throw F32 event on Monday.
Mashaykhi will look to add another medal to Oman's tally when he competes in the shot put F32 event on Friday.
Earlier at the Games, two Omani women – Raya al Abri and Shaikha al Hammadi – finished at 11th and 13th places respectively in the javelin throw F53/54 event.
While Raya's best throw was 8.95m, Shaikha threw a distance of 8.89m. China's Liwan Yang won the gold with a throw of 17.92m. Iran's Elham Salehi took the silver (16.49m) and India's Deepa Malik bagged the bronze (10.15m).