Advances in spectroscopic measurement and imaging technologies have become key tools in life sciences and materials science. However, for samples with weak optical responses, such as low-dimensional materials and living cells, high-power excitation light often introduces significant classical noise and causes non-negligible photodamage, thereby limiting the achievable signal-to-noise ratio (SNR) and the application scope. In this context, nonclassical light sources with unique quantum properties, such as entangled light and squeezed light, provide a promising route to surpass classical limits in SNR. This review focuses on the field of quantum-enhanced spectroscopy and imaging, and systematically reviews recent progress based on two important types of quantum light sources: entangled light and squeezed light. Owing to quantum correlations between photons, entangled light exhibits remarkable robustness against noise in applications such as correlation imaging, undetected-photon imaging, and ultrafast interferometric measurements. In contrast, squeezed light improves detection sensitivity and SNR by reducing quantum noise in the optical field, enabling enhanced performance in displacement sensing, plasmonic detection, and nonlinear microscopic imaging. Furthermore, this article systematically discusses the unique advantages of quantum light sources in improving SNR, reducing photodamage, enhancing temporal resolution, and increasing nonlinear conversion efficiency. It also analyzes key challenges that currently limit the practical implementation of quantum imaging technologies, including the low brightness of quantum light sources and large system losses. Finally, we discuss the future directions in this field.