Abstract: Monazite is the bearing-LREE (light rare earth elements) phosphate mineral that occurs all types of rocks. It is an essential mineral for understanding the formation processes and U-Pb dating, thus high precision analysis of monazite chemical composition has an important geological significance, and also provides reliable parameters for follow-up studies, such as EMPA CHIME dating and in-situ isotopic microanalysis. EMPA is an in-situ and non-destructive technique with an excellent spatial resolution (~1 μm). Due to that, based on the detailed wavelength scanning for SPI Monazite standard, we focus on discussing the important issues in analytical procedure of monazite chemical composition: accelerate voltage, beam current, time, spectrometer, analysis lines, detected limits, interference factor and standards, and obtain the chemical composition data that are finely consistent with the recommended values of the SPI monazite standard under the optimal analysis conditions. This paper presents the best analytical set-up of JEOL JXA-8530F Plus electron microprobe facility at State key laboratory for mineral deposits research, Nanjing University, particularly establishes the high precision analysis of the trace rare earth elements on large spectrometer of 140 mm Rowland circle. The relative standard deviations (RSD) of all element contents are less than 20% （0.05%-17.75%）and meet the accuracy requirement of integration analysis of monazite composition and geochronology.

Key words: monazite, chemical composition, high precision analysis