In terms of micro-nano structure measurement and determination, the fusion measurement of multiple traceability methods and measurement methods has become a trend of future measurement. Taking linewidth measurement as an example, it is difficult for a single metrological measurement method to provide accurate structural information, and it must rely on the full combination of multiple measurement methods (such as scanning electron microscopy measurement, light scattering measurement, and small-angle X-ray measurement) and traceability methods (metrological atomic force method and transmission electron microscopy measurement). The comparison level of the traceability chain with line width as the carrier is limited by the line width edge and the probe effect, which leads to the bottleneck of the comparison accuracy. Therefore, it is urgent to seek new alignment carriers as a breakthrough to improve the accuracy of traceability chain alignment. The idea of using a frequency-doubling silicon grating combining atomic lithography and soft X-ray interference lithography as the comparison carrier to carry out nano-length traceability comparison was proposed.A smaller-scale grating reference material with a grating spacing of 1/2 of the chromium atom self-traceable grating is developed based on the combination of atomic lithography and soft X-ray interferometric lithography, which can be directly traced to the wavelength corresponding to the atomic transition frequency and has the characteristics of self-traceability. Based on the characteristics of high precision and small size, it can be used as a comparison carrier, and the fusion measurement of nano-length traceability chain is proposed, which can effectively improve the measurement accuracy, equivalence and comparability of "top-down" and "bottom-up" traceability in China by studying the data fusion law between "top-down" and "bottom-up" traceability chains.The high-precision small-size grating can effectively avoid the error source of comparison with line width as the carrier (Fig.3), so as to improve the comparison accuracy of the two traceability chains. A new method for fusion metrology of nano-length traceability chain is proposed by using the frequency-doubling grating generated by the combination of chromium atom lithography and soft X-ray interferolithography as the carrier (Fig.1). The traceability chain comparison with the grating as the carrier satisfies the two necessary conditions of high precision and small size, and the accuracy of fusion measurement can be effectively improved through the study of measurement error transmission and data fusion law.On the basis of the grating made based on atomic lithography technology, the soft X-ray interferometric lithography technology is combined with the grating technology to produce a grating comparison carrier that can be used as the fusion measurement of nano-length traceability chain, and a new idea of using a frequency-doubling silicon grating combined with atomic lithography and soft X-ray interferometric lithography as a comparison carrier to carry out the comparison of nano-length traceability chain is proposed, which can effectively improve the measurement accuracy, equivalence and comparability level of "top-down" and "bottom-up" traceability in China. The successful implementation of the fusion measurement of nano length traceability chain mentioned in this paper is of great foundational significance for establishing a measurement system that integrates multiple traceability pathways and measurement methods and improving the level of advanced nano manufacturing in China.