Generally speaking, those who believe that there is no possibility of a large scale replacement with LED street lamps mainly take two factors into account: the quality and cost of LED street lamps. The quality problem exists in all aspects: luminous flux, luminous efficacy, luminous decay, thermal dissipation, color temperature, luminance distribution, stability, homogeneity, power supply and lifespan of other components. On the other hand, the cost of street lamps is several even dozens times higher than conventional street lamps. The LED street lamp, however, has its own strength in energy-saving, theoretically long service life and environmental-friendliness. As green environmental protection becomes a global theme today, it has won extensive support from governments and industries.