The Spaniard, winner at the Shanghai International Circuit last year, produced a time of one minute, 39.783 seconds to top the timesheets.
His team-mate Kimi Raikkonen could only manage a single lap after problems with the front of his car.
Mercedes driver and championship leader Nico Rosberg was second quickest, 0.398 seconds slower than Alonso.
Red Bull's Daniel Ricciardo (+0.989s) was over half-a-second off the pace, and narrowly quicker than McLaren's Jenson Button (+1.187s).
Australian rookie Ricciardo continues to outshine four-time defending drivers' championship winner Sebastian Vettel, who was ninth quickest.
Kevin Magnussen (McLaren), Jean-Eric Vergne (Torro Rosso) and Lewis Hamilton (Mercedes) were ahead of Vettel.
The Williams of Felipe Massa rounded out the top 10.