Ted Oh, the first-round leader, shot a 2-under 70 in the third round and is in a distant third place at 8-under par.
Jaidee bogeyed the second hole Saturday but calmed down from there. He collected two birdies on the front side to finish with a 1-under 35 on the first nine.
Jaidee and Montgomerie were tied with seven holes to play but Jaidee pulled away from the Scotsman. Jaidee birdied 13 and 18 to gain his two-stroke lead while Montgomerie parred the final seven.
'I had six putts in the last six holes and every one of them hit the lip at some stage. I've never done that before,' said Montgomerie, who shared last week's Volvo Masters Andalucia title with Bernhard Langer. 'On every putt, I though that's in, this time, this time, and it never went in. But never mind.'
Montgomerie finished with a 5-under 67 on Saturday.
Jaidee, last year's Asian PGA Tour Order of Merit champion, will play with Montgomerie in Sunday's final round.
'I played with Colin in the TCL Shootout on Wednesday and that was the first time I had played with him,' said Jaidee, who won the Myanmar Open at the start of the season. 'It will be a little bit different tomorrow but I am looking forward to it. I am sure playing with him will help lift my game.'
Liang Wen-chong is alone in fourth place at 7-under par, followed by Prayad Marksaeng, Charlie Wi and Michael Campbell, who share fifth place at minus-6.
Paul McGinley, the European Ryder Cup hero, shares eighth with Zhang Lian-wei, Bob May, Wang Ter-chang and Andrew Coltart. The group stands at 5-under-par 211.