The piece tittled The Falling Sunlight Enveloping the Sky is composed by QIN Wenchen in 2016 for a multi-string conjoined Guzheng.By breaking away from traditional 13-to 21-string tuning and pentatonic sounding Guzheng,the composer establishes his unique acoustic domain in this piece with personal aesthetics and cultural semantics though a reformed 25 plus 18-string conjoined Guzheng.This paper analyses the techniques of this piece from three perspectives:the design of core sonic materials,the development and structural significance of acoustic thematic elements,and the construction of aural space-time with its cultural connotations.Moreover, it delves into the composer's concept on sonic innovation,which seamlessly blends individuality,nature,and the essence of traditional Chinese artistry.