Election commission officials said the figure could go up by one to two per cent once the final tally is available.
Dealing a serious blow to separatist politics, enthusiastic voters stood in serpentine queues at several polling stations waiting for their turn.
The first phase of the five-phase polls for 15 seats on November 25 had witnessed a record 71.28 per cent polling.
"The latest figures that we have for the second phase of polls in Jammu and Kashmir is 71 per cent. We expect these numbers to go up by 1-2 per cent further," Deputy Election Commissioner Vinod Zutshi told reporters in Delhi.
Zutshi said that during the entire phase today, where 18 assembly seats in five districts went to polls, "no untoward incident" took place and the entire event was peaceful. Of the five districts, two were in the Valley and three in Jammu.
"There was no incident that vitiated the poll process in the state during this phase," he said, adding that "pretty heavy" voting was reported in Reasi and Udhampur districts.
Tuesday's poll percentage, the Deputy EC said, is higher than the figure of 61.04 per cent polling during the 2014 Lok Sabha polls and 68.79 per cent recorded during the 2008 Assembly elections.
The corresponding figures for voting today in the 5 districts stood at Reasi (80 per cent), Udhampur (76 per cent), Poonch (75 per cent), Kupwara (68 per cent) and Kulgam (above 60 per cent).
He said the weather was "very supportive" during the polls today and there was no snowfall. Tuesday's phase involved an electorate of 15.35 lakh. A total of 175 candidates, including four sitting ministers and 11 other sitting MLAs were in the fray.
There was a tight security cover in Kulgam and Kupwara districts following back-to-back attacks on two sarpanches by militants over the last two days in which one was killed.
Of the 18 constituencies, Handwara in north Kashmir Kupwara district was in focus as separatist-turned-mainstream politician Sajad Gani Lone is making a debut in Assembly elections after unsuccessfully contesting the Lok Sabha polls in 2009.
Although the cold weather conditions and heavy fog posed a hindrance in some areas in the early hours, voters started flocking the polling stations as the day progressed and the sun came out.