Large area, self-assembled Au-Si alloy nanocones are synthesized by vacuum electron-beam evaporation method at 450 degreesC. The formation mechanism is discussed based on the stress effect, interface energy, and Au-Si alloying process. The electron field emission properties of the self-assembled nanocones are studied based on current-voltage measurements and the Fowler-Nordheim equation. Low turn-on field (10 V/mum) with relatively high current density is obtained due to the nanocone-shaped structures with relatively rough morphology. The process temperature is lower than the melting point of ordinary glass. So our method is of great significance to the low-cost vacuum field emission devices fabrication. (C) 2003 Elsevier B.V. All rights reserved.