This paper focuses on the application of state design pattern in the secure user plane location（SUPL） and assisted global positioning system（A-GPS） based SUPL location platform（SLP）. It expatiates on function modules in the SLP based on the service control function （SCF） architecture

and most importantly

it puts forward the application of state design pattern in the SLP

which replaces the original service logic and service independent block（SIB） schema with task links of function modules.