The effects of polymers on the one-dimensional assembly of silica nanospheres (SNSs) in the liquid phase are systematically investigated using nonionic poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (abbreviated as PEO-PPO-PEO) triblock copolymers with varying hydrophilic-lipophilic balance (HLB) values. Scanning electron microscopy is employed for morphological observations of the polymer-mediated assemblies of SNSs on the basis of which the optimal pH for ID assembly (pH(1D)) is determined. To clarify the polymers' effects on the ID assembly of SNSs, the relationships between pHID and polymers' HLB values, the numbers of hydrophilic EO and hydrophobic PO units, and the relative ratio of N-PO/N-EO are examined. Zeta potential measurements are conducted to investigate the electrostatic repulsion among the SNSs in the presence of block copolymers. It is found that the relative hydrophilicity of the block copolymers greatly affects the balance of interactions in the ID assembly of SNSs. Block copolymers with large HLB values promote the ID assembly of SNSs under near-neutral pH conditions, whereas the block copolymers with small HLB values promote ID assembly under basic pH conditions. Therefore, the ID assembly of SNSs is achieved over an extensive pH range (7.5-9.5) through the employment of block copolymers of different hydrophilic and hydrophobic block lengths.