Abstract
In process of construction of national spatial reference system, aninterested problem is stability of the national height system for building ofhigh accurate quasigeoid model. Because the national height system had beenexploited a long time, many fist and second orders benchmarks had beendisplaced from social – economical and tectonical activities, repeat measurement of first andsecond orders networks requires many cost and time, then many countries onlyhad selected stable fist and second orders benchmarks to fit to the nationalquasigeoid model constructed by gravimetric data. In Vietnam, quasigeoid model VIGAC2017 had been constructed by this approach. Apart from that at present thenational spatial reference system is reference system closed with tectonicplate. This scientific article will consider above mentioned problems.
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