Abstract: Microalgae pose distinct advantages, including their ease of cultivation, high economic value, and wide applications. Nevertheless, the existing microalgae cultivation reactors fewquently encunter challenges such as high costs, low biomass yield, and slow growth rates. To enhance the cultivation efficiency of microalgae and overcome the constraints on their application potential due to low productivity, this study designed a thin-layer cross-flow photobioreactor (TCPBR) as well as a multi-TCPBR system with promising applications. The performance of the TCPBR was tested under various conditions, including inoculation concentration, illumination intensity, adhesion media, flow rate, and liquid level difference. Results indicated that when cultivating Klebsormidium sp. using the TCPBR at an inoculation concentration of 10 g/m² and light intensity of 85 µmol/(m²·s), the growth rate reached (15.00±0.34) g/(m²·d). Experimental with sieves of mesh sizes ranging from 300 to 1500 revealed that an 800-mesh sieve resulted in a retention rate for Klebsormidium sp. of up to (98.11±0.04)%. Additionally, when using five types of adhesion media, including acetate fiber membranes, PES membranes, sieves, canvas, and stencil, the growth rates exceeded (11.20±0.39) g/(m²·d), demonstrating that TCPBR can utilize more economical sieves or steel meshes for cultivating Klebsormidium sp. At a flow rate of 0.0153 m/s and a liquid level difference of 7.5 mm, the average growth rate of Klebsormidium sp. was (14.54±0.37) g/(m²·d), with manageable flow rates and liquid level differences and lower cultivation costs compared to similar wall-mounted reactors. When employing a multi-stage TCPBR formed by a series of single-layer TCPBR for cultivating Klebsormidium sp., the yield reached (40.18±0.68) g/(m²·d) for the same footprint area, significantly enhancing biomass yield. In conclusion, the TCPBR demonstrates high economic value and application potential in reducing cultivation costs, increasing biomass yield, and improving land utilization efficiency.