The Chinese entered Friday at The Dutch with a one-shot advantage and a 66 on day two moved him to 12 under ahead of England's Jonathan Thomson.
Countryman Li Haotong was then at eight under alongside Scot David Drysdale, a shot clear of Frenchman Benjamin Hebert, South Korea's Soomin Lee and England's Chris Wood.
Wu arrived in Spijk off the back of a second top ten of the season at the Omega European Masters as he looks for a third European Tour victory.
He needed the Access List to keep his playing privileges last season but is coming into form at just the right time, sitting 90th on the Race to Dubai Rankings presented by Rolex.
“I had a very good start today,” he said. “After two birdies on the first two holes I knew that my good feeling from yesterday was still there and I felt I could go on and make a lot more birdies.
“The wind came into play today and although it was not very strong it was still making it a lot more difficult. I really like the golf course here and its design so I am really enjoying this week.
“If the wind blows hard tomorrow it makes things very tricky for us but if it stays still then you will have to go out and keep being aggressive and make lots of birdies.”
Thomson recently lost a play-off at the Made in Denmark and he brought that form with him to Spijk as he matched the lowest nine-holes of the season to par.
The 22 year old made seven birdies after starting from the tenth to match Suttijet Kooratanapisan at the AfrAsia Bank Mauritius Open and Thorbjørn Olesen at the BMW International Open before coming home in level par for a 64.
Wu led by three after ten holes, sandwiching a bogey on the fifth with birdies at the first, second, sixth and tenth but Thomson's incredible charge with a 40-footer on the first and six birdies in a row from the 12th cut the advantage to one.
Thomson found the hazard off the tee on the first and Wu rolled home from just off the 12th green to re-establish his three-shot cushion.
A Thomson approach to eight feet on the second coupled with a Wu bogey on the 15th cut the lead back to one but Wu bounced back with an excellent tee-shot into the 16th and an 18-foot left-to-righter on the 17th.
An excellent battle was developing and while Thomson got on the sixth in two and put his approach to three feet on the next to once again trim the advantage, a bogey-bogey finish left Wu in command.
Drysdale was bogey-free playing alongside Wu and carded birdies at the fourth, fifth, seventh, eighth, tenth and 14th.
Two-time European Tour winner Li made gains on the sixth, ninth, tenth and 13th and, while he bogeyed the 16th, he bounced back on the next and made a sixth birdie of the day from the fringe on the last.
Lee made four birdies in a row from the 14th - including a chip-in on the 16th - in a 67 to sit alongside Wood and Hebert.
Wood made three birdies in six holes on the front nine but gave two of them back on the way in, while Hebert also turned in three under, eventually settling for a 69 after a three-putt on his final hole.
Italian Renato Paratore fired a 70 to sit at six under, a shot clear of a group of 12 players including two-time Major Champion and 2010 KLM Open winner Martin Kaymer.